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.

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