Seeing Stars with James Wooten: Comet ISON, Winter Solstice & the Geminid meteor shower

ev.owaThis is it. The final stargazing report of 2013. So let’s get to it, shall we?

Venus remains in the west at dusk for one more month. It outshines everything but the Sun and Moon, so you can begin observing it during deep twilight. Shortly after the new year begins, Venus shifts from the evening to the morning sky.

Jupiter will be up literally all night long early next month. In December 2013, then, it is not up at dusk but rises during the evening. Now you can see it rise in the northeast at about 8 p.m., just as Venus sets. By New Year’s Eve, Jupiter rises by 5:50 p.m., during twilight.

Mars remains in the morning sky. It continues to brighten a bit in the south at dawn.

Saturn has reappeared in the pre-dawn sky. Face southeast right before sunup to see it.

In December, the Big Dipper is below the horizon at dusk. As the Big Dipper sets, though, Cassiopeia rises. This is a pattern of five stars in a distinct W shape which lies directly across the North Star from the Big Dipper. Look for Cassiopeia high in the north on fall and winter evenings.

The Summer Triangle sets in the west. Watch for the Great Square of Pegasus almost overhead at dusk now and in the west by Christmas. Taurus, the bull, rises in the east. Look for the Pleiades star cluster above reddish Aldebaran. Dazzling Orion, the hunter, rises shortly after dusk (by month’s end, it is already up at dusk). As Orion enters the evening sky, we transition from the relatively dim evening skies of autumn to the brilliant stars of winter.

Unfortunately, it appears that Comet ISON did not survive its close passage to the Sun this past Thanksgiving. At 12:48 p.m. CST on Thurs., Nov. 28, ISON passed just 1.7 solar radii above the Sun’s surface. This proved to be too close, as the Sun’s gravity tore ISON apart, causing it to shed much of its gas and dust. This left only a small remaining fragment to continue on ISON’s orbital path, a fragment too small to put on a naked-eye show on December mornings. Binocular observers, though, can still give it a try.

You can still find information showing ISON’s position, or you can view the full path.

If ISON survives perihelion this Thanksgiving (it has about a 50/50 chance), we could see it quite well between Thanksgiving and Christmas. More on this in the December update.

Moon Phases in December 2013:

New: December 2, 6:21 pm
1st Quarter: December 9, 9:12 am
Full: December 17, 3:28 am
Last Quarter: December 25, 7:49 am

At 11:11 a.m. on Sat., Dec. 21, the Sun is directly overhead at the Tropic of Capricorn, the farthest point south where this is possible. This puts the Sun as low as possible in our sky, and marks the winter solstice. In the Southern Hemisphere, the Sun is as high as possible in the sky — this is the summer solstice for them.

Although the winter solstice is the shortest day, the earliest sunset occurred on about Dec. 2, and the latest sunrise will occur Jan. 10. That’s because the Earth speeds up on its orbit as it approaches perihelion (closest approach to the Sun) next month. This acceleration shifts sunrise, local noon, and sunset slightly later each day this month and next. The effect is smaller than that of the Sun taking a lower path across the sky, which normally dominates in causing earlier sunsets and later sunrises. But the Sun’s apparent path varies very little near the solstice itself, allowing the secondary effect of the Earth approaching the Sun to predominate. For most people, then, (those who witness sunset but sleep through sunrise), days will seem to lengthen throughout December, although they don’t really begin lengthening until Dec. 21.

The Geminid meteor shower peaks this month, as it does every December. Along with the Perseids in August, the Geminids are one of the two most reliable meteor showers, producing on average about 100 meteors per hour. The Geminids are unique among meteor showers because they are associated not with a comet but with an asteroid, 3200 Phaethon. This means that with Geminids, we see significant activity much earlier in the night than with other showers.

Most meteor showers peak in the hours immediately before dawn. This is because what plows through the debris field is the leading edge of the Earth, and that’s the side going from night into day. Since Phaethon is an asteroid, however, debris along its orbital path forms a shallower angle to Earth’s orbital path, meaning that we begin to face into the debris field as early as 9 or 10 p.m. Meteors will seem to “radiate” from the constellation Gemini, hence the name of the shower. However, they may appear anywhere in the sky.

As always, you see more meteors the farther you are from big city lights, which hide dimmer ones. Our George Observatory will be open at 5 p.m. on Friday night, Dec. 13, to 1 a.m. on Saturday morning, Dec. 14, for observing this meteor shower.

On most clear Saturday nights at the George Observatory, you can hear me do live star tours on the observation deck with a green laser pointer. If you’re there, listen for my announcement.

Don’t miss the Geminid Meteor Shower this Friday night! Here’s how, where and when to view

The annual Geminid Meteor Shower peaks this weekend, and we’ve got some tips for stargazers hoping to catch it.

The New Moon falls on Thursday, Dec. 13 this year, which should guarantee us nice, dark night for viewing. The Geminid Meteor shower peaks every December and is one of the best, most reliable showers, producing an average of 100 meteors per hour.

A Geminid meteor in 2009, as viewed from San Francisco
A Geminid meteor in 2009, as viewed from San Francisco, courtesy of Wikimedia Commons

Says HMNS Astronomer James Wooten: “The Geminids are unique among meteor showers because they are associated not with a comet but with an asteroid, 3200 Phaethon. This means that with Geminids, we see significant activity much earlier in the night than with other showers.”

That means instead of having to wait until the wee morning hours to see this beautiful shower, meteors will start radiating from the constellation Gemini as early as 9 or 10 p.m., although the shower will likely peak just before dawn.

As with all showers, the Geminid Meteor Shower will be best viewed away from city light pollution. The George Observatory will be open Friday night and into Saturday morning for observation. For directions to The George, located just an hour south of Houston, click here. Entry to Brazos Bend State Park is $7 per person; free for kids under 12. You don’t need any special equipment for viewing, just a chair, blankets and maybe some hot apple cider.

If you observe the meteor shower and are able to capture some great photos, share them with our Flickr group or by using the hashtag #hmnsgeminid on Twitter and Instagram. If Facebook’s your thing, post your photos on our wall, or tag us, and we’ll compile a credited album of everyone’s shots!

Seeing Stars with James Wooten: December 2012

Mars remains an evening object. It is low in the southwest at dusk.

Jupiter is now up all night long. Opposition — when Earth is directly between Jupiter and the Sun and Jupiter literally rises at sundown and sets at sunup — is Dec. 3. After that date, Jupiter only gets higher and more prominent in the evening sky. Face east/northeast at dusk and look for the brightest thing there (unless the Moon is also there), as Jupiter outshines all stars we see at night.

Sky Map November 2012

Venus remains in the east at dawn, continuing a spectacular morning apparition. It now appears a little closer to the horizon each morning.

Saturn is a little higher in the morning sky this month; look for it just above the much brighter Venus. Mercury is visible for the first half of the month at dawn.  Look just under Venus.

The autumn ‘intermission’ — when few bright stars are out at dusk — is over; brilliant winter stars enter the evening skies of December. Watch dazzling Orion rise as twilight ends. He rises with his three-starred belt almost vertical, halfway between reddish Betelgeuse and bluish Rigel. Orion’s belt points up to Aldebaran in Taurus, the Bull. This winter, the Bull also contains Jupiter.

Rising with Orion and far to his left are the twin stars Castor and Pollux, marking the heads of Gemini, the Twins.  By 8 p.m. in mid-month, the two Dog Stars have joined Orion. You can find Sirius, the brightest star we ever see at night, by drawing a line from Orion’s belt towards the horizon.

Moon Phases in December 2012:
Last Quarter                  December 6, 9:32 a.m.
New                               December 13, 2:41 a.m.
1st Quarter                    December 19, 11:19 p.m.
Full                                December 28, 4:22 a.m.

At 5:12 p.m. on Friday, Dec. 21, the Sun is directly overhead at the Tropic of Capricorn, the farthest point south at which it can be overhead. This puts the Sun as low as possible in our daytime sky, and as high as possible in the sky for anyone in the Southern Hemisphere. This also makes daytime as short as possible for us, and as long as possible for folks “down under.” Accordingly, this moment is the winter solstice in the Northern Hemisphere and the summer solstice in the Southern Hemisphere.

The Geminid Meteor Shower peaks this month, as it does every December. Along with the Perseids in August, the Geminids are one of the two most reliable meteor showers, producing on average about 100 meteors per hour. The Geminids are unique among meteor showers because they are associated not with a comet but with an asteroid, 3200 Phaethon. This means that with Geminids, we see significant activity much earlier in the night than with other showers.

Most meteor showers peak in the hours immediately before dawn. This is because what plows through the debris field is the leading edge of the Earth, and that’s the side going from night into day. Since Phaethon is an asteroid, however, debris along its orbital path forms a shallower angle to Earth’s orbital path, meaning that we begin to face into the debris field as early as 9 or 10 p.m. Meteors will seem to ‘radiate’ from the constellation Gemini, hence the name of the shower. However, they may appear anywhere in the sky.

As always, you see more meteors the farther you are from big city lights, which hide dimmer ones. Our George Observatory will be open Friday night, Dec. 14, into Saturday morning, Dec. 15, for observing this meteor shower.

On most clear Saturday nights at the George Observatory, you can hear me do live star tours on the observation deck with a green laser pointer. If you’re there, listen for my announcement.

To enjoy the stars in any weather from the comfort of the HMNS Planetarium, click here for a full schedule.

Would you like email updates on current events in the sky, at the planetarium, and at the George Observatory?  If so, send an email to astroinfo@hmns.org.

Go Stargazing! December Edition

Jupiter dominates this month’s evening skies.  It outshines all stars in the sky, so it’s easy to find.  Face south at dusk and look for the brightest thing there.

Mercury has emerged into the evening sky, and is visible at the beginning of this month.  Look low in the southwest at dusk, right over the point of sunset.  By mid-month, Mercury is again lost in the Sun’s glare; it re-aligns with the sun (is at inferior conjunction) on Dec. 19.

Venus remains a dazzling morning star.  Face southeast at dawn, and you can’t miss it.

Saturn is in the southeast at dawn, above the much brighter Venus.

mars-06-crop
Creative Commons License photo credit: chipdatajeffb

Mars is now lost in the sun’s glare; it will remain invisible to us all winter as Earth passes around the far side of the sun from it.

Look for the enormous Summer Triangle in the night sky, consisting of the stars Deneb, Vega, and Altair, in the west.  These stars were up all night long back in June and July, hence the name. The Great Square of Pegasus, not quite as bright as the Summer Triangle, is high in the south at dusk.  The star in its upper left hand corner is also the head of Andromeda.  Rising after Andromeda is Perseus, the hero that saved her life.  Facing north, you’ll see five stars in a distinct ‘M’ like shape—this is Cassiopeia, the Queen.  Her stars are about as bright as those in the Big Dipper, and she is directly across the North Star from that Dipper.  Taurus, the Bull rises in the northeast.  Look for the Pleiades star cluster at the feet of Perseus.  Dazzling Orion, the Hunter rises shortly after dusk (by month’s end, it is already up at dusk).  As Orion enters the evening sky, we transition from the relatively dim evening skies of autumn to the brilliant stars of winter.

Moon Phases in December 2010:

New Moon                             December 5, 11:36 a.m.

1st Quarter                            December 13, 7:58 a.m.

Full Moon                              December 21, 2:14 a.m.

Last Quarter                         December 27, 10:19 p.m.

Eclipse burning bright
Creative Commons License photo credit: ericskiff

The full moon of early Tuesday, December 21, enters the Earth’s shadow, causing a total lunar eclipse.  This eclipse is visible in its entirety from all of North America, including Houston.  The moon first encounters the Earth’s shadow (umbra) at 12:32 a.m.  This marks the beginning of the partial eclipse.  The moon takes just over an hour, until 1:40 a.m., to enter the shadow.  That is when totality begins.  In this eclipse, the Moon does not quite cross the center of Earth’s shadow but instead passes through the northern part of it.  Even so, the moon takes 74 minutes to cross to the other side of the shadow, so totality lasts from 1:40 to 2:54 a.m.  By 4:02 a.m., the moon has re-emerged from the shadow, and the eclipse is over.  Remember, seeing a lunar eclipse requires no special equipment at all; anyone who sees the moon sees the eclipse.  The only thing that could stop us from seeing this would be a cloudy night on December 20-21, 2010.  The next total lunar eclipse we see here in Houston occurs just after midnight on April 15, 2014.

At 5:42 p.m. on Tuesday, December 21, the sun is overhead at the Tropic of Capricorn, the most southerly latitude where the sun can be overhead.  This is therefore the winter solstice for those of us in the Northern Hemisphere, and the summer solstice for people south of the equator.

At Houston’s latitude, the earliest sunset of the year occurs Thursday, December 2.  Of course, days continue to shorten until the solstice, which makes sunset earlier and sunrise later.  However, Earth is also accelerating as it approaches perihelion (closest approach to the sun) in early January.  This causes sunrise, local noon, and sunset to occur slightly later each day.  This close to the solstice, the second effect actually predominates, so sunset gets a little later during December even while the days are getting shorter.  As you head out to ring in the New Year, notice that sunset on New Year’s Eve is about 10 minutes later than it is now.

2009 Leonid Meteor (cropped, afterglow closeup)
Creative Commons License photo credit: Navicore

The Geminid meteor shower peaks every year in mid-December, this year on the 14.  This shower and the Perseids in August are the two most reliable showers of the year, producing about 1 or two meteors per minute.  The Geminids are not as popular, though, because of colder nights (yes, sometimes even in Houston) and a greater chance of cloudy skies.  Still, it’s worth a look if the skies are clear.  Unlike most meteor showers which are comet debris, the Geminids originate from an asteroid (3200 Phaethon.  The shallower angle between this debris path and Earth’s orbit means that Earth rotates us towards the debris field before midnight.  We can thus observe meteors from late evening all the way until dawn.  Meteors will seem to radiate from the constellation Gemini, hence the shower’s name.