Bright Stars in the Sky

Though this blog mainly focuses on comets, asteroids and meteors, the blog postings which seem to get the most hits are those referring to bright stars visible in the sky. This shouldn’t be too surprising since the most frequent (and often times most obvious) sites in the sky are bright stars low near the horizon during the hours most people are out and about (just after sunset and right before sunrise).

This post will provide a quick sweep of the early evening and early morning sky to highlight some of the brighter objects in the sky.

EVENING:

Most of the bright star action as soon as it gets dark in the evening is located in the southeastern sky. Not only do we have the usual Winter Sky suspects, but Jupiter joins them this year. Located in the middle of Gemini to the right of the pair of bright Gemini stars, Castor and Pollux, Jupiter outshines every star and planet in the evening sky. A few recent high-resolution images of Jupiter can be seen in this post.

The brightest star in the sky (though still half the  brightness of Jupiter) is Sirius. This time of the year Sirius gets a lot of attention because of its location close to the horizon near sunset. When so low Sirius may appear to not only change brightness but also to vary in color if the air is turbulent.

Night sky for northern mid-latitudes around 6:45 pm. Chart created with Stellarium. Credit: Carl Hergenrother.

Night sky for northern mid-latitudes around 6:45 pm. Chart created with Stellarium. Credit: Carl Hergenrother.

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Sirius is a blue star but can appear to change color rapidly. The reason for this is due to the Earth‘s atmosphere. Turbulence in the atmosphere causes the star’s light to be “bounced” all over the place. The light of the star is made up of many different colors which all “bounce” around differently. As a result, normally blue Sirius can appear to rapidly switch between many different colors when it is close to the horizon (meaning its light is passing through more atmosphere than usual). All stars experience this effect, it is just that Sirius‘ brightness makes it more evident. Watching Sirius when low in the sky with a telescope or just your eyes can be one of the best sights in the night sky.

Why does Sirius twinkle and change colors while brighter Jupiter does not? Check out Phil Plait’s explanation on his Bad Astronomy site.

More on Sirius can be found here.

MORNING

Some early risers may notice brilliant Venus low in the southeast. Only a few weeks ago Venus was a brilliant evening object in the southwest right after sunset. After passing roughly between the Earth and Sun, the brightest planet is now beginning a long stint as the ‘Queen of the Morning Sky’.

View of the early morning eastern sky from northern mid-latitudes around 6:35 am. Chart created with Stellarium. Credit: Carl Hergenrother.

View of the early morning eastern sky from northern mid-latitudes around 6:35 am. Chart created with Stellarium. Credit: Carl Hergenrother.

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Before leaving the morning sky, Robert Lunsford was able to image Venus through his 9.25″ telescope. At that time the planet was a very slender crescent. Venus shows a similar phase at this time as well.

Image of Venus taken by Robert Lunsford from ChulaVista, CA on 2013 January 6 with a C9.25 telescope. Credit: Robert Lunsford.

Image of Venus taken by Robert Lunsford from ChulaVista, CA on 2013 January 6 with a C9.25 telescope. Credit: Robert Lunsford.

Saturn from the VATT

On my last night at the VATT, the clouds rolled in right before dawn. Rather than close up early I tried a little Saturn observing. Thanks to the use of a narrow-band Vilnius S filter (central bandpass ~0.655 nm), a shutter that can take short exposures and the clouds, I was able to get a few good shots of the ringed planet.

Usually when astronomers image the planets they use video rate cameras and take 1000s of images. Specialized software is then used to pick out the best of the images which are then co-added together to bring out subtle details. The VATT4K is not optimized for such rapid imaging so I was limited to taking only a few images. Still the image shows lots of good detail. It sure helped that the mountain was experiencing sub-arc second seeing.

The image below was one of the best.

Saturn_2013Jan21_Hergenrother

The Moon, Saturn, Mars and Spica Team Up This Evening

Only a week or so ago, the Moon made a beautiful grouping with 2 planets (Venus and Jupiter) and a bright star (Aldebaran) in the early morning sky. Tonight (evening of July 24) the Moon will team up with a different collection of planets (Mars and Saturn) and a bright star (Spica).

Once it is dark enough to see some stars this evening, look to the SW. The chart below shows the relative positions of the objects. The bright star to the lower left of Saturn and upper left of the Moon is Spica. A B-type or blue giant, Spica is the 15th brightest star in the sky. It is located 260 light years away and produces as much light as 1500 Suns with a mass of 10 Suns.

View of the Moon-Mars-Saturn-Spica grouping in the SW sky during the evening of July 24. Credit: Carl Hergenrother (chart made with Stellarium)

 

Venus and Jupiter Put on an Early Morning Show

[Editor's note: I notice that lots of people are still finding this now a few years old post. If you are trying to find out what those bright stars in the eastern evening sky (Sirius and Jupiter) and eastern Morning sky (Venus) are (Jan/Feb 2014), go to the front page of this blog at transientsky.wordpress.com for the latest posts.]

I see there have been lots of searches recently about the 2 bright ‘stars’ in the early morning eastern sky.

The show is being put on by the planets Venus (the brighter and lower one) and Jupiter. Also in line with the two is the Pleiades open star cluster (above the 2 planets) and Aldebaran , the brightest star in Taurus (below the two planets). The two planets will spend the next few weeks close together. On the morning of July 15 a thin crescent Moon will add even more to the show.

So for all of you early risers out there who have been watching these two, congratulations. As for the rest of us (myself included), set your clocks for an hour before sunrise, find a clear view of the eastern horizon and enjoy the show.

Image

A chart of Venus and Jupiter an hour or so before sunrise on the morning of 2012 June 30. Credit: Carl Hergenrother/Stellarium.

Watch the Moon Join the Venus-Jupiter Show!

Two weeks ago Jupiter and Venus had an amazing close approach in the evening sky. Now the two are separated by ~10°. Though Jupiter appears to be the one that is quickly moving further down night after night, it is actually Venus that is quickly moving by ~1° per day to the east relative to the stars. It just so happens that the stars are moving to the west by ~1° per day so Venus appears to be in the same part of the sky relative to the horizon.

Tonight and tomorrow night the Moon joins in the fun. Tonight (evening of March 25) the Moon will pair up with Jupiter while tomorrow night (evening of March 26) it will spend the evening with Venus.

To put the three objects in perspective, here are their distances from Earth for tonight. The Moon is by far the closest object at a distance of 0.0027 AU (~252,000 miles from the center of the Earth). Venus is the next one out at a distance of 0.72 AU (66.9 million miles) which is 265 times further away than the Moon. While distant Jupiter is 5.76 AU away (535 million miles) or 8 times further away than Venus. In case you are wondering, Mars which is visible as a bright red star in the east during the evening is almost the same exact distance away from Earth as Venus (0.72 AU).

In The Sky This Month – April 2011

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of April 2011.

April 2011 Highlights
* Saturn is the only easily visible planet
* The rest of the naked eye planets congregate in the morning sky at the end of the mont

Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.

Planets

Moon - The table below lists important lunar dates for the month, including the phases of the Moon and nights of lunar-planetary and lunar-stellar conjunctions.

Apr 3 - New Moon
Apr 7 - Moon 2° from Pleiades
Apr 8 - Moon 7° from bright star Aldebaran
Apr 11 - First Quarter Moon 9° from bright star Pollux
Apr 12 - Moon 5° from Beehive Cluster
Apr 14 - Moon 5° from bright star Regulus
Apr 17 - Moon 8° from Saturn and 2.5° from bright star Spica
Apr 18 - Full Moon
Apr 20 - Moon 3° from bright star Antares
Apr 25 - Third Quarter Moon
Apr 30 - Moon 6.6° from Venus

Saturn – This month Saturn is at opposition. As a result, the ringed planet is at its brightest for the year (magnitude +0.4) and is also visible all night long though it is best around midnight. At the start of the month Saturn may be too low in the SE at dusk to be easily seen but by month’s end it is far enough off the horizon at dusk to be easily seen. Saturn is a slow moving planet and takes 29 years to circle the Sun as well as 29 years to do one circuit around the ecliptic constellations. As has been the case all year long, Saturn is still located in Virgo about 11-13° from 1st magnitude Spica.

Apr 3 - Saturn at Opposition
Apr 17 - Saturn and Moon 8° apart

Venus, Mercury, Mars and Jupiter -  The long slow grind towards superior conjunction continues. This month Venus rises only an hour or so before the Sun and never gets very high in the ESE to E sky. Though Venus is a difficult sight for northern observers it is worth searching out at the end of April. During the last week of the month (and into May) Venus will be visited by 3 planets in the best planetary alignment of the year. Starting around the 25th, Mercury peaks above the eastern horizon 40 minutes before sunrise. Over the next few nights, Mars and Jupiter join the show. Use the crescent Moon on the 29th and 30th to point the way.

Apr 30 - Moon 6.6° from Venus

Meteors

Meteor activity is near a seasonal minimum in April. The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During April mornings, 10-12 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Lyrids (LYR)

The Lyrids are usually good for 10-20 meteors per hour under a dark sky. This month the just past Full Moon will make the shower difficult to observe. So these remnants of Comet Thatcher will probably go unobserved except by automated video systems and only the most dedicated of visual observers.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Starting this month, info on most of the minor showers will be provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Additional information on these showers and other minor showers not included here can be found at the following sites: Wayne Hally’s and Mark Davis’s NAMN Notes, and the International Meteor Organization’s 2011 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None this month…

Binocular Comets (V = 6.0 – 8.0)

None this month…

Small Telescope Comets (V = 8.0 – 10.0)

C/2011 C1 (McNaught)

It seems the past couple of years have seen a bright Comet McNaught and this year is no different. The 58th comet discovery by Rob McNaught and 74th from Siding Spring Observatory, C/2011 C1 was first seen on February 10th of this year. Though intrinsically faint, the comet is currently being reported as bright as magnitude 9.0. CCD images taken by the author on Apr 1 UT confirm that the comet is between magnitude 9.0 and 9.5 at this time (see image below). Unfortunately this will probably be as bright as the comet gets as it passes perihelion on April 17 at a distance of 0.88 AU from the Sun. It is also slowly moving away from Earth with a geocentric distance of 0.95, 1.06 and 1.22 AU from Earth at the star, middle and end of the month. Comet C/2011 C1 travels the length of Aquarius before ending the month near the Pisces/Pegasus border.

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Asteroids

Binocular and Small Telescope Asteroids (V < 8.0)

(4) Vesta

Vesta is the brightest asteroid in the Main Belt. This is due to its high albedo (or reflectivity) which causes it to reflect ~42% of the light that strikes it. Vesta is also peculiar in that it appears to have evidence of volcanism on its surface. Similar to the Moon, Vesta may be covered with large expanses of frozen lava flows. It is classified as a V-type asteroid and is the only large asteroid with this classification. Many of the smaller V-type asteroids are chips of Vesta blasted off it by past asteroid and comet impacts. Vesta has dimensions of 347x336x275 miles or 578×560×458 km.

The maps below were created from images taken with the Hubble Space Telescope. The geography is dominated by a large impact crater located near the south pole (the blue ‘donut’ in the elevation map). Perhaps this crater is the result of the impact that blasted off the smaller V-type asteroids. We’ll know more this summer when NASA’s Dawn spacecraft enters orbit around Vesta for a full year. Currently the encounter is scheduled for July 2011 to July 2012.

Images and models of the shape of asteroid (4) Vesta. In the upper left is a real HST image, to the upper right is a model of Vesta’s shape, and on the bottom is an elevation map . Credit: NASA/STScI.

Vesta spends the month around magnitude 7.6 to 7.3 as it moves eastwards through western Capricornus.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Vesta from Heavens Above.

In The Sky This Month – March 2011

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of March 2011.

March 2011 Highlights
* Mercury and Jupiter dazzle after evening twilight
* Saturn is up all night
* Venus slowly loses altitude before dawn

Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.

Planets

Moon - The table below lists important lunar dates for the month, including the phases of the Moon and nights of lunar-planetary and lunar-stellar conjunctions.

Mar 1 - Moon 1.6° from Venus
Mar 4 - New Moon
Mar 6 - Moon 6° from Jupiter
Mar 11 - Moon 2° from Pleiades
Mar 12 - First Quarter Moon
Mar 12 - Moon 7° from bright star Aldebaran
Mar 15 - Moon 9° from bright star Pollux
Mar 16 - Moon 5° from Beehive Cluster
Mar 17 - Moon 5° from bright star Regulus
Mar 19 - Full Moon
Mar 20 - Moon 7.5° from Saturn
Mar 21 - Moon 2.5° from bright star Spica
Mar 24 - Moon 3° from bright star Antares
Mar 26 - Third Quarter Moon
Mar 28 - Moon 1.5° from asteroid Vesta
Mar 31 - Moon 5.5° from Venus

Mercury and Jupiter – The innermost planet has its best evening apparition of the year this month (for observers in the northern hemisphere). From mid-month till the end of the month, Mercury will be observable low in the western sky a half-hour or so after sunset. As an added bonus, Jupiter will be located nearby. The two will be closest on Mar 15 when they will only be 2° from each other. By the end of the month both planets will be located too close to the Sun to be easily seen.

Mar 6 - Moon 6° from Jupiter
Mar 15 - Mercury and Jupiter within 2° of each other
Mar 23 - Mercury at Greatest Elongation East

Saturn – Saturn starts the month rising a few hours after sunset. By the end of the month it is only a few days from opposition (on April 3) and rises just moments after sunset. Located in Virgo, the ringed planet is a close match in brightness (mag +0.4) to Spica, the brightest star in Virgo (mag +1.0). Saturn spends the entire month within 10° of Spica.

Mar 20 - Moon 7.5° from Saturn

Venus –  On Mar 1, Venus rises almost 2 hours before the Sun in the eastern sky though this drops to just a little over an hour by the end of the month.

Mar 1 - Moon 1.6° from Venus
Mar 31 - Moon 5.5° from Venus

Mars – Too close to the Sun for observation.

Meteors

Meteor activity is near a seasonal minimum in March. The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During March mornings, 10-12 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

None this month…

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Starting this month, info on most of the minor showers will be provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Additional information on these showers and other minor showers not included here can be found at the following sites: Wayne Hally’s and Mark Davis’s NAMN Notes, and the International Meteor Organization’s 2011 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None this month…

Binocular Comets (V = 6.0 – 8.0)

None this month…

Small Telescope Comets (V = 8.0 – 10.0)

None this month…

Asteroids

Binocular and Small Telescope Asteroids (V < 8.0)

(4) Vesta

Vesta is the brightest asteroid in the Main Belt. This is due to its high albedo (or reflectivity) which causes it to reflect ~42% of the light that strikes it. Vesta is also peculiar in that it appears to have evidence of volcanism on its surface. Similar to the Moon, Vesta may be covered with large expanses of frozen lava flows. It is classified as a V-type asteroid and is the only large asteroid with this classification. Many of the smaller V-type asteroids are chips of Vesta blasted off it by past asteroid and comet impacts. Vesta has dimensions of 347x336x275 miles or 578×560×458 km.

The maps below were created from images taken with the Hubble Space Telescope. The geography is dominated by a large impact crater located near the south pole (the blue ‘donut’ in the elevation map). Perhaps this crater is the result of the impact that blasted off the smaller V-type asteroids. We’ll know more this summer when NASA’s Dawn spacecraft enters orbit around Vesta for a full year. Currently the encounter is scheduled for July 2011 to July 2012.

Images and models of the shape of asteroid (4) Vesta. In the upper left is a real HST image, to the upper right is a model of Vesta’s shape, and on the bottom is an elevation map . Credit: NASA/STScI.

Vesta spends the month around magnitude 7.7 as it moves eastwards through eastern Sagittarius.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Vesta from Heavens Above.

In The Sky This Month – December 2010

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of December 2010.

December 2010 Highlights
* Great Total Lunar Eclipse for the Americas and Eastern Asia on Dec 21
* Geminid Meteor Shower peaks on Dec 14
* Jupiter dominates the evening sky, while…
* Venus dominates the morning sky
* Comet 103P/Hartley 2 slowly fades as it moves away from the Earth and Sun

Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.

Planets

Moon - The big event this month is a Total Lunar Eclipse on the night of Dec 20/21. The Moon will be located nearly overhead during the peak of the eclipse for North American observers.

The start of the umbral eclipse (when the darkest part of Earth’s shadow covers the Moon) will occur at 6:32 UT (1:32 EST / 12:32 CST / 11:32 MST / 10:32 PST) with mid-eclipse at 8:16 UT (3:16 EST / 2:16 CST / 1:16 MST / 12:16 PST)

The table below lists important lunar dates for the month, including the phases of the Moon and nights of lunar-planetary and lunar-stellar conjunctions.

Dec 1 - Moon 7° from Saturn
Dec 2 - Moon 6° from Venus and 3° from Spica
Dec 5 - New Moon
Dec 6 - Moon 0.8° from Mars
Dec 7 - Moon 2° from Mercury
Dec 11 - Moon 5° from Neptune
Dec 13 - First Quarter Moon 7° from Jupiter
Dec 14 - Moon 6° from Uranus
Dec 19 - Moon 1.5° from Pleiades and 8° from Aldebaran
Dec 21 - Full Moon and Total Lunar Eclipse
Dec 23 - Moon 8° from Pollux
Dec 24 - Moon 4° from Beehive Cluster
Dec 25 - Moon 5° from Regulus
Dec 28 - Third Quarter Moon 7° from Saturn
Dec 29 - Moon 3° from Spica
Dec 31 - Moon 7° from Venus

Mercury – Mercury is in the middle of a evening apparition at the start of the month. It’s all downhill (literally) after that as the innermost planet creeps back into the bright twilight and out of view by mid-month. At the end of the month Mercury is back as it peeks above the SE horizon right before dawn.

Dec 1 - Greatest Elongation East
Dec 7 - Moon 2° from Mercury 

Mars - Mars is practically out of view this month for most of us. Those with exceptionally clear skies and unobstructed view of the SW sky in the evening might still catch a glimpse of this +1.3 magnitude planet.

Dec 6 - Moon 0.8° from Mars

Jupiter (and Uranus, too...) - The 'King of the Planets' continues his reign as the uncontested 'King of the Evening Sky'. though fading from magnitude -2.5 to -2.3, nothing but the Moon rivals it in brightness. Located on the Pisces/Aquarius border, Jupiter is easy to find in the south-south-east as it gets dark.

If you have a pair of binoculars or small telescope take a look at Jupiter. See if you can see any of its 4 bright Galilean moons or its large atmospheric belts (there are usually 2 prominent belts but 1 has recently disappeared though it may make a comeback at any time). In addition, Jupiter is within 2.9° of +5.8 magnitude Uranus on Dec 1 and 0.7° on Dec 31.

Dec 13 - First Quarter Moon 7° from Jupiter

Saturn - Saturn rises a few hours before the Sun. Located in Virgo, the ringed planet is a close match in brightness (mag +0.9) to the Spica, the brightest star in Virgo (mag +1.0). Saturn spends the entire month within 9-10° of Spica. It's rings are slowly opening up and are currently 9° from edge-on.

Dec 1 - Moon 7° from Saturn
Dec 28 - Moon 7° from Saturn

Venus - After passing through inferior conjunction in late October , Venus is now the dominant sight in the morning sky. On Dec 1, Venus rises 3 hours before the Sun in the eastern sky. By the end of the month, it is up almost 4 hours before sunrise. Unlike this year's evening apparition which was poorly placed, Venus' current stay in the morning sky will be a good one for northern observers.

Dec 2 - Venus at its brightest (magnitude -4.5 to -4.9 depending on the source)
Dec 2 - Moon 6° from Venus
Dec 31 - Moon 7° from Venus

Meteors

Meteor activity is still quite high in December. The year is usually split in 2 with January through June having low rates with few major showers while July through December (really through the 1st week of January) have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During September, 10-16 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Geminids (GEM) [Max Date = Dec 14, Max Rate = ~60-120 per hour under dark skies]

Along with the Perseids of August, the Geminids are one of the best meteor showers delivering great displays year after year. This year's Geminids are nicely timed with the First Quarter Moon will be setting around midnight.

According to Sirko Molau's analysis of video data, the Geminids are already observable at the beginning of the month though their rates are very low. The peak is predicted for the night of December 13/14 though numerous meteors should be visible for a day or two on either side of the peak. With a radiant near the star Castor in the constellation of Gemini, the Geminids are one of the rare major showers that are observable before midnight and can be observed as early as 8:00 pm though rates are usually best after 10:00 pm (though with the caveat for this year that the Moon will spoil the show until it sets around midnight). Under a dark rural moon-less sky, the Geminids can produce as many as 100+ meteors per hour. Observers under suburban skies will see lower rates.

The Geminids are the result of the break-up and subsequent activity of the "asteroid" (3200) Phaethon. Why asteroid in quotes? Most meteor showers come from comets yet Phaethon is on a very non-cometary orbit and has never shown any cometary activity. There is still much scientific discussion about what exactly Phaethon is.

More details on the Geminids and their parent "asteroid" Phaethon will be posted as we get closer to its peak.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Starting this month, info on most of the minor showers will be provided on a weekly basis by Robert Lunsford's Meteor Activity Outlook.

Additional information on these showers and other minor showers not included here can be found at the following sites: Wayne Hally's and Mark Davis's NAMN Notes, and the International Meteor Organization's 2010 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V = 6.0 - 8.0)

Comet 103P/Hartley 2 - Comet 103P/Hartley 2 continues its retreat from the Earth and Sun. Well past its late October peak in brightness, the comet starts December around magnitude 6 and should steadily fade to around magnitude 8 by the end of the month.

.103P was discovered at Siding Spring Observatory (Australia) on March 15, 1986 by  Malcolm Hartley. With an orbital period of 6.47 years, the comet's orbit currently stretches from 1.06 AU to 5.89 AU from the Sun. Though not an especially big comet, this year it passed 0.12 AU from Earth on October 21 allowing the comet to get much brighter than usual.The comet starts the month at a distance of 1.16 AU from the Sun and 0.29 AU from Earth. By mid-month it will be 1.24 AU from the Sun and 0.36 AU from Earth. At the end of the month, Hartley 2 will be 1.36 AU and 0.46 AU from the Sun and Earth, respectively. 

Even though the comet is currently 6th magnitude and theoretically bright enough to be an easy binocular object, in reality this is a difficult object to observe. With a coma diameter approaching 1° across, the light of the comet is spread over a wide area. As a result, even small amounts of light pollution renders much of the coma invisible. Dark skies are always a plus and will help in observing this challenging comet.

The comet is located in the southern part of the winter Milky Way. The start of December sees the comet in Puppis just to the south of the bright open clusters M46 and M47. By the end of the month it will have retrograded into Canis Major. It is a morning object and is visible after midnight.

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On November 4 the NASA EPOXI (ex-Deep Impact) spacecraft encountered Hartley 2 giving us close-up views of the comet's nucleus. This is the xth comet visited by a spacecraft after Comets 21P/Giacobini-Zinner (1985), 1P/Halley (1986), 19P/Borelly (2001), 81P/Wild 2 (2004), 9P/Tempel 1 (2005). On February 15, 2011, Tempel 1 will be the first comet to be re-visited by a spacecraft.

A finder chart for Comet Hartley 2 can be found at Comet Chasing and Sky and Telescope.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida's Comet Homepage.

Small Telescope Comets (V = 8.0 - 10.0)

Comet P/2010 V1 (Ikeya-Murakami) - Probably the surprise comet of the year, Comet Ikeya-Murakami is a rare visual find. Not long ago most bright comets were discovered by amateur astronomers visually through the eyepiece of their telescopes without the help of computers. Nowadays, the professional surveys are able to scan large swathes of sky and with the help of digital CCD cameras and detection software find most comets.

The reason Ikeya and Murakami could discover P/2010 V1 is probably because it is a small and usually weakly or even inactive comet. The fact that the comet was not visible to other comet hunters (including Ikeya) a day or two before discovery suggests it has recently undergone an outburst. CCD images of its rapidly expanding coma also point to a recent event. At discovery the comet was as bright as magnitude 7.5 to 8.0. At the start of this month the comet is around magnitude 9 to 10 and, baring another outburst, should quickly fade.

Another interesting thing about this comet is its orbit. With an aphelion of only ~4.2 AU, the comet does not extend far enough to reach the orbit of Jupiter. Unlike most cometary orbits, this orbit is very asteroidal and suggests that it more closely related to volatile-rich Main belt comets than the typical comet from the outer Solar System.

Perihelion occurred on 2010 Oct. 11 at 1.57 AU. The comet is now outbound and at mid-month is located 1.68 AU from the Sun and 2.21 AU from Earth. Starting the month in Virgo the comet will cross into Libra by mid-month.

A finder chart for Comet Ikeya-Murakami can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida's Comet Homepage.

Asteroids

Binocular and Small Telescope Asteroids (V < 9.0)

(7) Iris

Iris is an inner Main-Belt asteroid that can occassionally get as bright as any asteroid. This year, Iris will not get as bright but will still become a binocular object at opposition on January 24 at magnitude 7.9. During December, it is located in the constellation of Cancer a few degrees to the southwest of the Beehive Cluster. It starts the month at magnitude 8.9 and ends it at magnitude 8.3.

With a size of 240 x 200 x 200 km, Iris is the 5th largest stoney S-type asteroid. It was discovered in 1847 by John Russel Hind, the 1st of 10 asteroids he discovered.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Ceres from Heavens Above.

In the Sky This Month – October 2010

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of October 2010.

October 2010 Highlights 
* Comet 103P/Hartley 2 is a naked eye object under very dark skies
* Jupiter dominates the eastern evening sky
* Uranus remains within 3 degrees of Jupiter all month
* Orionids meteor shower will be washed out by bright Moonlight

Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.

Planets

Moon - The table below lists important lunar dates for the month, including the phases of the Moon and nights of lunar-planetary and lunar-stellar conjunctions.

October 1 - Last Quarter 
October 2 - Moon 8° from Pollux 
October 3 - Moon 4° from Beehive Cluster 
October 4 - Moon 5° from Regulus
October 7 - New Moon 
October 9 - Moon 3° from Venus
October 10 - Moon 3° from Mars
October 11 - Moon 3° from Antares 
October 14 - First Quarter  
October 20 - Moon 7° from Jupiter and Uranus
October 23 - Full Moon
October 25 - Moon 1.5° from Pleiades 
October 26 - Moon 8° from Aldebaran
October 29 - Moon 8° from Pollux
October 30 - Last Quarter
October 30 - Moon 4° from Beehive Cluster

Venus – Venus starts the month very low in the SW sky at sunset. By the end of twilight it has already set. Conditions only get worse as it descends towards the Sun. By mid-month, Venus is invisible in the evening sky. After passing inferior conjunction on the 29th, Venus will rapidly climb higher in the morning sky and should be visible by early next month.

October 1 - Venus 7° S of Mars
October 9 - Moon passes within 3.4° of Venus 
October 29 - Venus at inferior conjunction

Mars – Mars continues its slow grind lower in the southwestern evening sky. At a relatively faint (for a planet anyway) magnitude of +1.5, Mars is only visible low in the SW during evening twilight.

October 1 - Mars 7° N of Venus
October 10 - Moon passes within 3° of Mars

Jupiter (and Uranus, too…) – This month the ‘King of the Planets’ is also the ‘King of the Evening Sky’. At magnitude -2.8 Jupiter is the brightest ‘star’ in the eastern evening sky. It is currently located on the Pisces/Aquarius border.

If you have a pair of binoculars or small telescope take a look at Jupiter. See if you can see any of its 4 bright Galilean moons or 2 large atmospheric belts. In addition, Jupiter is within 3° of +5.7 magnitude Uranus all month long.

October 20 - Moon within 7° of Jupiter and 6° of Uranus

Saturn – Saturn starts the month behind the Sun. By the end of the month, the +0.9 magnitude planet can be seen very low  in the eastern sky during dawn. It is currently located in Virgo and will be for the next year or so.

October 1 - Saturn at conjunction with Sun

Mercury - Mercury is rapidly dropping towards the Sun at the beginning of the month. By  the end of the first week of October it will be too close to the Sun to be seen.

October 17 - Mercury at Superior Conjunction

Meteors

Meteor activity is near a yearly maximum in October. The year is usually split in 2 with January through June having low rates with few major showers while July through December (really through the 1st week of January) have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During September, 10-16 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Orionids (ORI) [Max Date = Oct 21, Max Rate = ~20-70 per hour]

The Orionids are one of the most reliable and productive showers of the year. Another point in their favor, is their high level of activity over the course of ~5 nights or so. This gives ample opportunity to catch a few Orionid meteors. Unfortunately this year the nearly Full Moon will severely hamper watching this shower.

The meteors that make up the Orionid shower were originally released by the one comet everyone has heard of, Comet Halley. Computer simulations of the past movements of Halley and its dust suggest that many of this year’s Orionid meteors were released by Halley between 1265 BC and 910 BC (for some points of reference, the Trojan War took place around 1200 BC and King David ruled around 1000 BC).

The Orionids are usually active from Oct 3 to Nov 11 with a broad peak between Oct 18 and 24. During their peak, rates can be as high as 20-70 meteors per hour. During the last  two years rates reached 40-45 meteors per hour which is nearly half the rate observed in 2007 (70 per hour). With a bright Moon-lit sky, actual rates will be much lower making this a dificult year to see the Orionids.

The Orionids appear to come from an area in northern Orion. This area, called the radiant, rises around 10pm local time. It is best to wait till the radiant is high in the sky before looking for meteors (say 1am). The radiant is highest around 3:30am which is the best time to look. As you can see on the sky chart, the Moon is almost on top of the radiant. Meteors can appear anywhere in the sky so you don’t have to look at the radiant.

More can be found at earlier Orionids posting from 2008 and 2009.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Starting this month, info on most of the minor showers will be provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Additional information on these showers and other minor showers not included here can be found at the following sites: Wayne Hally’s and Mark Davis’s NAMN Notes, and the International Meteor Organization’s 2010 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

Comet 103P/Hartley 2 – Comet 103P/Hartley 2 should be the comet of the year. Currently as bright as magnitude +5.5 to +6.5 magnitude, naked eye sightings of this comet have already been reported from very dark sites. The comet will continue to brighten during the course of the month.

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103P was discovered at Siding Spring Observatory (Australia) on March 15, 1986 by  Malcolm Hartley. With an orbital period of 6.47 years, the comet’s orbit currently stretches from 1.06 AU to 5.89 AU from the Sun. Though not an especially big or active comet, this year it passes 0.12 AU from Earth on October 21 allowing the comet to get much brighter than usual.

The comet starts the month at a distance of 1.12 AU from the Sun and 0.18 AU from Earth. By mid-month it has moved into Andromeda and will be 1.21 AU from the Sun and 0.29 AU from Earth. Closest approach to Earth occurs on October 21 at 0.12 AU while closest approach to the Sun happens on October 28 at 1.06 AU. At the end of the month, Hartley 2 will be 1.06 AU and 0.14 AU from the Sun and Earth, respectively.

Last month there was concern that the comet was running much fainter than expected. Due to the large diffuse nature of its coma, many observers were underestimating the brightness of the comet. The comet still appears to be a little fainter than predicted but it should still brighten to a nice magnitude +4.5 to +5.0 by the end of October.

Under very dark skies the comet can already be seen with the naked eye. For most of the rest of us, Hartley 2 is a large (30’+) diffuse fuzz ball. Under my moderately light polluted sky (LM +5.5), the comet was a difficult object in 10×50 binoculars. As always, the darker the sky the better.

The comet is traversing the winter Milky Way and starts the month in Cassiopeia before running the length of Perseus and Auriga and ending the month in Gemini. It is visible all night long at the start of the month but becomes solely a morning object by mid-month.

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In early November the NASA EPOXI (ex-Deep Impact) spacecraft will encounter the comet giving us close-up views of the comet’s nucleus.

A finder chart for Comet Hartley 2 can be found at Comet Chasing and Sky and Telescope.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Binocular Comets (V = 6.0 – 8.0)

None

Small Telescope Comets (V = 8.0 – 10.0)

None

Asteroids

Binocular and Small Telescope Asteroids (V < 9.0)

(6) Hebe and (8) Flora

These 2 large inner Main Belt asteroids will move in tandem this fall. Both are S-type asteroids with similar compositions and albedos. (6) Hebe is the larger of the pair (205 x 185 x 170 km). Recent research suggests that it is the source of many ordinary chondrite meteorites and near-Earth asteroids. (8) Flora is a little smaller (136 x 136 x 113 km) and is the largest surviving member of a numerous asteroid family created by a long ago impact.

This month Hebe is retrograding in Cetus and will fade from magnitude 7.7 to 8.4. Just across the border in Aquarius Flora fades from magnitude 8.5 to 9.1.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Hebe from Heavens Above.

In The Sky This Month – September 2010

This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of September 2010.

September 2010 Highlights

* Venus, Mars and Spica together in evening sky at start of month
* The above 3 joined by the Moon on the 11th
* Jupiter at opposition (21st) with Full Moon (23rd) and Uranus nearby
* Mercury has a good morning apparition
* Comet 103P/Hartley 2 is bright enough for small telescopes and binoculars

Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <transientsky1@yahoo.com>.

Planets

Moon - This month brings a new addition to the “In The Sky This Month” lineup. The table below lists important lunar dates for the month, including the phases of the Moon and nights of lunar-planetary and lunar-stellar conjunctions.

September 1 - Last Quarter
September 1 - Moon 1° South of Pleiades
September 1 - Moon 8° North of Aldebaran
September 4 - Moon 8° SSW of Pollux
September 5 - Moon 4° SSW of Beehive Cluster
September 8 - New Moon
September 9 - Moon 7° SSW of Saturn
September 10 - Moon 3° SSW of Spica
September 11 - Moon 5° SSW of Mars
September 12 - Moon 0.6° from Venus
September 14 - Moon 2° NNW of Antares
September 15 - First Quarter
September 23 - Full Moon
September 23 - Moon 7° from Jupiter
September 28 - Moon 1.5° from Pleiades
September 29 - Moon 8° North of Aldebaran

Saturn – Saturn is located low in the west during evening twilight. By month’s end the +1.0 magnitude planet will be too close to the Sun to be seen easily by most observers.

September 9 - Moon within 7° of Saturn

Mars – Mars is the second of three planets visible in the west after sundown. This month +1.5 magnitude Mars starts a few degrees to the upper right of brilliant Venus. Though the planets will slowly move apart they will stay within 7° of each other all month long.

September 11 - Moon passes within 5° of Mars

Venus – Venus is the third and by far the brightest planet visible in the early evening (at magnitude -4.6 to -4.8). For northern observers this is a poor apparition. Though the planet is at its brightest and located almost as far from the Sun as it gets, the angle between the ecliptic and the horizon results in the planet staying close to the horizon. A clear view of the WSW horizon is needed in order to see Venus (and Mars and Saturn, as well). The planet sets 1.5 hours after sunset at the start of September and less than an hour by the end of the month. See the notes in the Mars section above about seeing Mars in the vicinity of Venus.

September 1 - Venus within 1° of Spica
September 11 - Moon passes within 0.6° of Venus
September 27 - Venus at its brightest (magnitude -4.6)

Jupiter (and Uranus, too…) – This month Jupiter rules the heavens. On the 21st, the ‘King of the Planets’ will be at opposition (meaning it is located directly opposite the Sun on the sky). All month Jupiter will shine at its brightest (near magnitude -2.9). Opposition also means it will be visible all night long, rising in the evening, reaching its highest elevation around midnight and setting during dawn.

If you have a pair of binoculars or small telescope take a look at Jupiter. See if you can see any of its 4 bright Galilean moons or 2 large atmospheric belts. In addition, Jupiter is within a degree of +5.7 magnitude Uranus all month long.

September 18 - Jupiter and Uranus within 0.8° of each other
September 21 - Jupiter and Uranus at opposition
September 23 - Moon within 7 of Jupiter and 6 of Uranus

Mercury - Mercury starts the month too close to the Sun to be seen. By mid-month, it is in the midst of its best morning apparition (for northern observers).

September 19 - Mercury at Greatest Elongation West (18 from Sun)

Meteors

Meteor activity is near a yearly maximum in September. The year is usually split in 2 with January through June having low rates with few major showers while July through December (really through the 1st week of January) have high rates with many major showers.

Sporadic Meteors

Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During September, 10-16 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

No major showers this month.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Starting this month, info on most of the minor showers will be provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.

Additional information on these showers and other minor showers not included here can be found at the following sites: Wayne Hally’s and Mark Davis’s NAMN Notes, and the International Meteor Organization’s 2010 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None

Binocular Comets (V = 6.0 – 8.0)

Comet 103P/Hartley 2

If it behaves as expected, Comet 103P/Hartley 2 should be the comet of the year. Currently magnitude +11.5, the comet is predicted to reach naked eye visibility (for dark sky observers) in October/November.

103P was discovered at Siding Spring Observatory (Australia) on March 15, 1986 by  Malcolm Hartley. With an orbital period of 6.47 years, the comet’s orbit currently stretches from 1.06 AU to 5.89 AU from the Sun. Though not an especially big or active comet, this year it passes 0.12 AU from Earth on October 21 allowing the comet to get much brighter than usual.

The comet starts the month in the faint constellation of Lacerta at a distance of 1.31 AU from the Sun and 0.39 AU from Earth. By mid-month it has moved into Andromeda and will be 1.21 AU from the Sun and 0.29 AU from Earth. By month’s end, the comet will just south of the brightest star in Cassiopeia (Alpha Cas) and 1.13 AU from the Sun and 0.19 AU from Earth.

[Note: The following paragraph has been updated to reflect recent observations.]

Now that the Moon is out of the morning sky, visual observers have been able to estimate the brightness of the comet. Observations over the past few days show the comet to be around magnitude 8.5. This is very close to its predicted brightness and suggests the comet may live up to its expected maximum brightness of 5th or 6th magnitude this Oct/Nov. The comet is large and diffuse with much of its brightness contained in a large, faint outer coma. As a result, the comet may appear much fainter to observers using large telescopes or observing from bright sites. By the end of the month the comet should be around magnitude 6.5 making it an easy binocular object.

In early November the NASA EPOXI (ex-Deep Impact) spacecraft will encounter the comet giving us close-up views of the comet’s nucleus.

A finder chart for Comet Hartley 2 can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Small Telescope Comets (V = 8.0 – 10.0)

Comet 10P/Tempel 2

’10P’ says it all. This was only the 10th comet to be observed at a 2nd apparition meaning we’ve been following this comet for a long time. Discovered by prolific German comet discoverer Ernst Wilhelm Leberecht Tempel in Marseille, France on July 4, 1873, Tempel 2 has been observed at nearly every return since then. The comet’s current orbit brings it to within 1.42 AU of the Sun on July 4 and to within 0.65 AU of Earth in late August.

The comet is currently at a brightness of 9.0 to 9.5 magnitude. This is a large diffuse object so it will be more difficult to see than your average 9th magnitude comet or deep sky object. From my moderately light polluted backyard and 12″ telescope, the comet was a difficult object and was estimated to be magnitude 10.0. From a dark site and 30×125 binoculars, the comet was much brighter (magnitude 9.5), larger and easier to see. The added brightness was probably due to the dark site allowing me to see much more of the comet’s coma.

At mid-month the comet will be 1.61 AU from the Sun and 0.67 AU from Earth. Tempel 2 is a morning object moving through the constellation of Cetus.

A finder chart for Comet Tempel 2 can be found at Comet Chasing.

A nice collection of images can be found at the VdS-Fachgruppe Kometen (Comet Section of Germany) and Seiichi Yoshida’s Comet Homepage.

Asteroids

Binocular and Small Telescope Asteroids (V < 9.0)

(1) Ceres

Ceres is the biggest asteroid in the Main Belt with a diameter of 585 miles or 975 km. It is so big that it is now considered a Dwarf Planet. Classified as a carbonaceous (carbon-rich) Cg-type asteroid, there are suggestions that it may be rich in volatile material such as water. Some even propose that an ocean exists below its surface. Ceres is the other target of NASA’s Dawn spacecraft which is scheduled to visit it in 2015.

This month Ceres is an evening object moving from Ophiuchus into Saggitarius. The asteroid will start the month at magnitude 8.6 and fade to magnitude 9.0 by the end of the month.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Ceres from Heavens Above.

(6) Hebe and (8) Flora

These 2 large inner Main Belt asteroids will move in tandem this fall. Both are S-type asteroids with similar compositions and albedos. (6) Hebe is the larger of the pair (205 x 185 x 170 km). Recent research suggests that it is the source of many ordinary chondrite meteorites and near-Earth asteroids. (8) Flora is a little smaller (136 x 136 x 113 km) and is the largest surviving member of a numerous asteroid family created by a long ago impact.

This month Hebe is retrograding in Cetus and will brighten from magnitude 8.0 to 7.7. Just across the border in Aquarius Flora will brighten from magnitude 8.4 and peak at magnitude 8.2 in early September before fading back to 8.4 at the end of the month.

A finder chart (needs to be flipped upside down for Northern Hemisphere observers) can be found at the Royal Astronomical Society of New Zealand. Finder chart for Hebe from Heavens Above.

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