Lunar Eclipse on Sunday

[update: changed the time of mid-eclipse to 2:47 UT from 2:48 UT. thanks to Joe Stieber for catching the error. the one minute difference doesn’t change the rest of the article.]

Sunday evening will see the last of the recent tetrad of lunar eclipses for observers in the Americas. The eclipse will occur in the morning for observers in Europe, Africa, and western Asia. This eclipse has been hyped a bit more than usual due to the Moon being a ‘Super Moon’. What that means is the Moon is at the close part of its orbit to Earth and appears a little bit larger than usual. Regardless, all total lunar eclipses are worth seeing and this one will be very nice for western US observers as it will be located low on the horizons making for some nice views. Occurring during the early evening also means we don’t have to be up at weird hours of the night to see this one. This is especially convenient for showing the kids.

The Moon will enter the penumbra of Earth’s shadow at 00:12 UT though most observers will have a difficult time noticing any darkening of the Moon until around ~00:40 UT (8:40 pm EDT, 7:40 pm CDT). At that time the Moon will be below the horizon for Tucson and most observers in the Mountain and Pacific time zones.  The Moon enters the umbra of Earth’s shadow and really starts to get dark at 1:07 UT (9:07 pm EDT, 8:07 pm MDT, 7:07 pm MDT). At Tucson the Moon rises at 1:09 UT (6:09 pm PDT) only 1 minute after the start of the partial eclipse and 7 minutes before sunset. As the Moon gets higher and the sky gets darker it will become easier to see even as Earth’s shadow takes a bigger and bigger bit out of it.

The total phase of the eclipse begins at 2:11 UT (10:11 pm EDT, 9:11 pm CDT, 8:11 pm MDT, 7:11 pm PDT). The middle of the eclipse and the time when the Moon should appear darkest occurs at 2:47 UT (10:47 pm EDT, 9:47 pm CDT, 8:47 pm MDT, 7:47 pm PDT. Totality ends at 3:23 UT (11:23 pm EDT, 10:23 pm CDT, 9:23 pm MDT, 8:23 pm PDT) and the whole show should be over (meaning no obvious darkening of the Moon visible by ~5:20 UT.

Here in Tucson, the Moon will appear to rise at due east and will be observable in the southeastern sky for the entire eclipse.

2015_lunar_eclipse
View of the eastern horizon at the time of mid-eclipse for Tucson, Arizona. Chart created with Stellarium.

If you have a pair of binoculars or are taking images of the eclipse, note that two other relatively bright solar system objects are near the Moon. The planet Uranus is located ~15° to the due east or lower left of the Moon. At that time Uranus will be magnitude 5.7 (barely visible to naked eye observers from dark sites) and located 19.98 AU from the Sun and 19.02 AU from Earth (that’s 1.86 million miles from the Sun and 1.77 million miles from Earth). The Moon will be 0.0024 AU from the Earth (222,000 miles from the center of the Earth) or ~7900 times closer than Uranus. To the southeast of the Moon and about 11° away is the brightest asteroid, (4) Vesta. It will be 2.42 AU (225 million miles) from the Sun and 1.43 AU (133 million miles) from Earth or ~600 times further away than the Moon. Vesta will be a little fainter than Uranus at magnitude 6.2. Use the star chart below to find Uranus and Vesta.

2015_lunar_eclipse_vesta_uranus
Location of Uranus and asteroid Vesta relative to the eclipse Moon on Sunday evening Sep. 27. Chart created with Stellarium.

The next lunar eclipse will be on 2016 March 23 but will be a rather poor penumbral eclipse (meaning the darkest part of the shadow doesn’t cross the Moon). The next series of total lunar eclipses occur on 2018 January 31, 2018 July 27, and 2019 January 19. The first and third of this triad are visible in the US. Go to the NASA Lunar Eclipse page for more detail on these and other lunar eclipse.

In the Transient Sky – August 2012

August 2012 Highlights
* Perseid meteor shower peaks on the morning of August 12
* Moon occults Venus on August 13
* Moon located between Venus and Jupiter during the peak of the Perseids
* Mars, Saturn and Spica form a tight group mid-month (Moon joins on the 21st)
* Mercury is visible in the morning after mid-month

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

Evening Planets

Mars and Saturn – Mars and Saturn are visible in the WSW sky during early evening hours. The two are joined by the bright 1st magnitude star Spica. The three are similar in brightness with the brightest being Saturn at magnitude +0.8 followed by Spica at magnitude +1.0 and Mars at +1.1 to 1.2. Saturn moves slowly relative to the stars and will be within 5° of Spica all month. Mars is moving much faster. At the start of the month Mars is ~7° of Saturn and Spica. On the 13th and 14th Mars passes in between Saturn and Spica. The three will form a nice line only ~5° long on those evenings. The Moon joins to make a quartet on the evening of the 21st.

Morning Planets

Jupiter – The largest planet rises around 1-2 am at the start of the month and around 11 to midnight at the end of the month. At magnitude -2.2 to -2.3 it is much brighter than the evening planets. Jupiter is currently moving slowly through the constellation of Taurus. The Moon is nearby on the mornings of August 11 and 12 (the night before and the night of the Perseid peak).

Venus – Venus rises about 3.5 hours before the Sun this month. In fact, on August 15 it is at Greatest Elongation from the Sun. In a telescope the planet will appear half-illuminated. The Moon is close by on the mornings of August 13th and 14th. The Moon passes so close to Venus that it actually passes in front of the planet for all of Mexico and the United States and all but the extreme NE corner of Canada. The event can also be seen from Japan, the Koreas, NE China and eastern Siberia. In the United States, the occultation is visible during the late afternoon on August 13. The Moon and Venus will be very low in the sky for eastern observers. The view is easier towards the western half of the country.

Mercury – The innermost planet is too close to the Sun for easy observation at the beginning of the month. By 2nd week of August it is rapidly climbing out of the dawn twilight. Use the Moon to spot Mercury on the morning of the 15th (Mercury to the lower left of the Moon) and 16th (Mercury above a very thin crescent Moon).

Meteors

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. Meteor activity is at an annual peak this month.

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 June mornings, 7 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Perseids (PER)

The Perseids are one of the 2 annual showers worth getting up early for. This year the peak will occur on the morning of August 12. The Moon will be up at that time though it shouldn’t hamper meteor watching too much.

From the International Meteor Organization’s 2012 Meteor Calendar:

Recent IMO observations found the timing of the mean or “traditional” broad maximum varied between λ⊙ ∼ 139.8° to 140.3°, equivalent to 2012 August 12, 07h to 19h30m UT. No additional peaks are anticipated this year, but this does not guarantee what will occur!

Although the Moon is a waning crescent, three days after last quarter on August 12, it will rise from mid-northern locations around local midnight to one a.m. Its brightness and relative proximity to the Perseid radiant should be considered more of a nuisance than a deterrent, even so. Such mid-northern latitudes are the more favored for Perseid observing, as from here, the shower’s radiant is usefully observable from 22h—23h local time onwards, gaining altitude throughout the night. The near-nodal part of the “traditional” maximum interval would be best-viewed from eastern Asia east to far western North America (with increasing moonlight for places further east in this zone), assuming it happens as expected. All forms of observing can be carried out on the shower, though unfortunately, it cannot be usefully observed from most of the southern hemisphere.

The best time to look will be after about 1-2 am on the night of August 11/12. Meteors will appear to radiate from the constellation of Perseus in the northeast sky.

Over the past five years, the Perseids have peaked with zenithal hourly rates (ZHR) of 58 (in 2011), 91 (in 2010), 173 (in 2009), 116 (in 2008) and 93 (in 2007). These are the rates that would be seen under perfectly dark skies, with no Moon and with the radiant overhead. In reality these conditions are never really met especially if you live anywhere near a city. Still observed rates of 20-40 meteors per hour are possible even under suburban skies.

The Perseids were produced by Comet 109P/Swift-Tuttle which orbits the Sun once ever ~135 years. This comet was discovered by American astronomers Lewis Swift (Marathon, New York) and Horace Tuttle (Cambridge, Massachusetts) in July of 1861. During that return the comet reached a bright 2nd magnitude and developed a tail up to 30° long. The comet returned late in 1992 and brightened up to 4th-5th magnitude. Based on our updated knowledge of Swift-Tuttle’s orbit it is now known that the comet was also seen in 1737 and likely seen in 188 AD and 69 BC.

Back in 1992, Tim Spahr and I used the Catalina schmidt to take a photographic image of Comet Swift-Tuttle (seen below).

Comet Swift-Tuttle observed with the University of Arizona Catalina Schmidt in 1992. This is a scan of a photographic image taken by Tim Spahr and Carl Hergenrother. Credit: Carl Hergenrother/Tim Spahr.

The best time to look will be after about 1-2 am on the night of August 12/13. Meteors will appear to radiate from the constellation of Perseus in the northeast sky.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are 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 International Meteor Organization’s 2012 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

In the Transient Sky – June 2012

July 2012 Highlights
* Venus and Jupiter share the early morning sky
* The Moon, Venus, Jupiter and Aldebaran are within 5° of each other on the morning of the 15th
* Mars and Saturn slowly fade in the evening sky
* Mercury continues a nice apparition in the evening sky

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

Evening Planets

Mercury – This month Mercury finishes off a rather good evening apparition for northern observers. On the 1st Mercury is located a few degrees above the WNW horizon an hour after sunset. It will quickly drop (as well as slowly fade) out of sight by the 2nd week of July.

Mars – Mars is the brightish reddish “star” to the SW early in the evening. Mars reached opposition (the point opposite the Sun on the sky) in early March. In July, it fades from magnitude +0.9 to +1.1. The red planet will spend the month moving eastwards through western Virgo. The Moon visits on the evenings of the 23rd and 24th.

Saturn – Saturn reached opposition on April 15 at a distance of 8.75 AU (813 million miles or 1.3 million km) from Earth. This month it continues making a nice but distant pair (~5°) with the bright 1st magnitude Spica. Both can be seen to the South at the end of twilight. Saturn will fade from magnitude +0.7 to +0.8. The Moon visits on the mornings of the 24th and 25th. Mars is quickly closing in on Saturn and Spica and will make a nice trio of similarly bright “star” in mid-August.

Morning Planets

Jupiter and Venus – Last March, these two put on a nice display in the evening sky. After parting for a few month, they are back together, this time in the early morning sky. On the 1st, the two are located within ~5° of each other. Jupiter is further from the horizon at magnitude -2.0. Venus is much brighter at magnitude -4.6 and further down. About 3° below Venus is the brightest star in Taurus, 1st magnitude Aldebaran. Both planets will shift down relative to the stars with Venus passing within 1° of Aldebaran on the morning of the 9th. On the morning of the 15th the Moon will join the two planets and Aldebaran. All 4 will be located within an area 7° across. Definitely wake up early to see this.

Meteors

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. Meteor activity really takes off this month.

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 June mornings, 7 or so Sporadic meteors can be observed per hour from a dark moonless sky.

Major Meteor Showers

Southern Delta Aquariids

This shower will be spoiled by the nearly Full Moon this year. Luckily the even better Perseids in August won’t be bothered by the Moon.

Minor Meteor Showers

Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are 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 International Meteor Organization’s 2012 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None this month.

Binocular Comets (V = 6.0 – 8.0)

None

Small Telescope Comets (V = 8.0 – 10.0)

Comet 96P/Machholz

Comet 96P/Machholz is the only comet that will be brighter than 10th magnitude this month. And even it will be a difficult object as it will be located very close to the Sun.

This comet was discovered the old fashioned way, by an astronomer looking through a telescope. No cameras, whether photographic or digital, were used. Don Machholz first spotted 96P on 1986 May 12 from Loma Prieta peak in California. It currently takes ~5.3 years to orbit the Sun.

It has one of the smallest perihelion distances of any short-period comet at 0.12 AU. For this go-around, the comet will reach perihelion on July 14. Though the comet will be very bright at perihelion, estimates range from magnitude +2 to -2, it will be located within a few degrees of the Sun at that time making it invisible to everyone except for a few Sun-watching spacecraft. With difficulty, observers with telescopes in the Southern hemisphere will be able to watch the comet rapidly brighten but also rapidly approach the Sun for the first few days of July. Those of us in the Northern hemisphere have a chance of spying the quickly fading comet during the last few nights of July.

Date            RA        DEC    Delta   r   Elong    V
2012 Jul 01   05h 35m  -02d 44'  0.955 0.521   31    9.5
2012 Jul 11   06h 51m  +14d 14'  1.092 0.211   11    5.1
2012 Jul 21   09h 01m  +30d 30'  1.003 0.291   17    6.6
2012 Jul 31   11h 10m  +27d 03'  0.894 0.587   35   10.0

RA = Right Ascension, DEC = Declination, Delta = distance from Earth in AU
r = distance from the Sun in AU, Elong = elongation from Sun in degrees
V = Visual magnitude

In the Transient Sky – June 2012

The big event this month (at least for folks around the northern Pacific basin) is the annular solar eclipse on May 20. As for planets, Venus, Mars and Saturn are easy to see in the evening.

June 2012 Highlights
* Transit of Venus on June 5
* Partial Lunar Eclipse on June 3 
* Venus rockets out into the morning sky
* Mars fades but still is high in the evening sky
* Saturn is easily seen in eastern evening sky
* Mercury starts a nice apparition in the evening sky

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>.

Partial Lunar Eclipse

The Moon follows up last month’s annular eclipse with a partial eclipse on the morning of June 4th. The eclipse can be seen  North and South America, Australia, eastern parts of Asia and all across the Pacific Ocean. Only 37% of the Moon will enter the umbra so it will be far from a total eclipse. Here in the US, the Moon enters the dark umbra at 10:00 UT (6:00 am EDT, 5:00 am CDT, 4:00 am MDT, 3:00 am PDT). Maximum eclipse occurs an hour and three minutes later. For more information on when and where this event can be seen go to Science News @ NASA Science.

Venus Transit of the Sun

On June 5th, Venus will pass in front of the Sun for the first time since 2004 and the last time till 2117. For more info please visit the Transit of Venus website.

Planets

Evening Planets

Mars – Mars is the brightish reddish “star” to the SW early in the evening. Mars reached opposition (the point opposite the Sun on the sky) in early March. In June, it fades from +0.5 to +1.0. The red planet will spend the month moving eastwards from the constellation of Leo into Virgo. The Moon visits on the evening of the 25th and 26th.

Saturn – Saturn reached opposition on April 15 at a distance of 8.75 AU (813 million miles or 1.3 million km) from Earth. This month it continues making a nice but distant pair with the bright 1st magnitude Spica. Both can be seen to the South at the end of twilight. Saturn will fade from magnitude +0.5 to +0.7. The Moon visits on the mornings of the 27th.

Morning Planets

Mercury – This month Mercury starts a rather good apparition for northern observers in the evening. It reaches its highest point above the horizon on June 22.

Jupiter – A month past conjunction with the Sun, Jupiter can be seen slowly rising out of morning twilight. During the later half of the month Jupiter and Venus make a nice pair once again (similar to their showing this Spring in the evening) against the backdrop of the Pleiades and Hyades clusters of Taurus. The Moon is located near Jupiter on the morning of the 17th.

Venus  – After its spectacular transit of the Sun on the 5th Venus enters the morning sky. Not quite reaching as high as Jupiter, the brightest planet will be easy to see just before the start of morning twilight by the end of the month. The Moon pays it a visit on the morning of the 18th.

Meteors

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. Background rates start to tic upwards in June.

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 June mornings, 7 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. Info on many minor showers are 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 International Meteor Organization’s 2012 Meteor Shower Calendar.

Comets

Naked Eye Comets (V < 6.0)

None this month.

Binocular Comets (V = 6.0 – 8.0)

None

Small Telescope Comets (V = 8.0 – 10.0)

Comet 96P/Machholz

Comet 96P/Machholz is the only comet that may be brighter than 10th magnitude this month. And even then it will only be brighter than 10th magnitude for the last day or two of the month. Next month the comet will be much brighter though it will also be located closer to the Sun.

This comet has one of the smallest perihelion distances of any short-period comet at 0.12 AU. For this go-around, the comet will reach perihelion on July 14. During June it will only be visible from the Southern Hemisphere. Northerners will get their chance towards the end of July. At the start of June, it will be located 1.19 AU from the Sun and 1.17 AU from Earth. Though rapidly brightening it will still only be a faint magnitude 14. By the end of the month the comet will have brightened to magnitude 10 or a little brighter. It will close out the month at a distance of 0.55 AU from the Sun and 0.95 AU from Earth.

Don Machholz first spotted 96P back on May 12, 1986 at magnitude 9.7. Though the comet can get very bright (up to magnitude -2) it is always located too close to the Sun for observation when that bright. By the time the comet has moved far enough from the Sun for easy observations it will have faded to 8th or 9th magnitude. It currently takes ~5.3 years to orbit the Sun.

Date            RA        DEC    Delta   r   Elong    V
2012 Jun 01   01h 59m  -31d 44'  1.168 1.190   66   14.2
2012 Jun 10   02h 58m  -26d 41'  1.031 1.015   59   13.1
2012 Jun 20   04h 12m  -17d 24'  0.942 0.798   48   11.7
2012 Jun 30   05h 27m  -04d 13'  0.949 0.549   32    9.8

RA = Right Ascension, DEC = Declination, Delta = distance from Earth in AU
r = distance from the Sun in AU, Elong = elongation from Sun in degrees
V = Visual magnitude

Total Lunar Eclipse Tonight

The astronomical event of the month is Tuesday morning’s Total Lunar Eclipse. With the Moon riding high in the sky near the border of Taurus and Gemini, the eclipse is perfectly placed for observers in North America.

Check out the Shadows and Substance site for animations and graphics about tonight’s eclipse.

The table below lists times for all 4 American time zones. Though the penumbral part of the eclipse starts at 5:28 UT, most people won’t see a noticeable darkening of the Moon until sometime around 6:00 UT.

                              UT    EST     CST     MST     PST
Start of Penumbral Eclipse   5:28  12:28a  11:28p  10:28p   9:28p 
Start of Partial Eclipse     6:32   1:32a  12:32a  11:32p  10:32p
Start of Total Eclipse       7:40   2:40a   1:40a  12:40a  11:40p
Mid-Eclipse                  8:17   3:17a   2:17a   1:17a  12:17a
End of Total Eclipse         8:54   3:54a   2:54a   1:54a  12:54a
End of Partial Eclipse      10:02   5:02a   4:02a   3:02a   2:02a
End of Penumbral Eclipse    11:06   6:06a   5:06a   4:06a   3:06a

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.