What’s “Up” This Month – Celestial Happenings This December

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Photo courtesy of Pixabay

Our resident astronomer James Wooten is back, and he’s here to tell you what to look up for this month! From meteor showers to solar events, December is shaping up to be an exciting end of the year. And  of course he will give you the update on when and where to find your favorite constellations and planets. You can impress your date this December with your stellar knowledge of the night sky! (By the way, Saturday night star gazing at the George Observatory is a great place to take a date) So sit back and put your astronomer hat on, because here’s the low-down on the high up!

 

Moon Phases in December 2016:

Moon Phases

1st Quarter: December 7, 3:03am Full: December 13, 6:06pm 3rd Quarter: December 20, 7:56pm New: December 29, 12:53am

 

What are the Planets Up to this Month?

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Venus is a little higher in the evening sky this month. Look low in the west southwest in evening twilight. Venus noticeably approaches Mars more than in previous months. 

Mars is now in the southwest at dusk. Mars continues to fade each night as Earth leaves it farther and farther behind.

Mercury is visible just after sunset this month. Face west in twilight, and look low in the sky over the point where the Sun set, especially around the 11th.  Mercury isn’t as brilliant as Venus, but it easily outshines the stars near it in the sky, so it’s not too hard to find. 

Jupiter is much higher in the morning sky this month. Look in the south southeast at dawn now, and more towards due south by month’s end.  

Saturn  is behind the Sun and out of sight this month.

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. We are beginning to face away from the center of the galaxy, looking at stars behind us in our own part of our galaxy (the Orion Spur). 

December Constellation Map

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This star map shows the Houston sky at 8 pm CST on December 1, 7 pm CST on December 15, and dusk on December 31.  To use the map, put the direction you are facing at the bottom.

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. We are beginning to face away from the center of the galaxy, looking at stars behind us in our own part of our galaxy (the Orion Spur).

Celestial Happenings to Watch for this month:

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Photot courtesy of Wikimedia

Geminid Meteor Shower

The Geminid meteor shower peaks every year around mid-December.  This year, it’s the night of December 13-14 (although they’re active from December 4-17).  Unfortunately, this year we have a full moon on that night, which will hide most meteors. 

Winter Solstice

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By Jecowa at the English language Wikipedia, CC BY-SA 3.0, Link

At 4:44 am on Wednesday, December 21, the Sun will appear overhead as seen from the Tropic of Capricorn, the farthest point south where this is possible. That’s because Earth’s North Pole is tilted as far as possible away from the Sun at that time. That’s why this is our winter solstice, the day when we have more night and less daylight than any other.  Below the equator, this is the summer solstice because the South Pole is tilted towards the Sun as much as possible.

You will notice, however, that sunset on New Year’s Eve is up to ten minutes later than on December 1.  Why, if the 31st is closer to the solstice?  Although the shortest day (least daylight) occurs on December 21, the earliest sunset occurs for us about December 1.  This is because the Sun’s apparent position in our sky varies like a sine wave; there is little difference in the Sun’s apparent height for about a month before and after the solstice.  Due to Earth’s tilt, the Sun does indeed take a shorter, lower path across the sky on December 21 than on December 1, but only by about 1.5 degrees (your pinky at arm’s length blocks one degree).  Meanwhile, Earth is slightly accelerating as it approaches perihelion just after the new year.  This makes both sunrise and sunset happen a little earlier each night during December.  Near the solstice, this small effect can dominate.  Since most of us sleep through sunrise and watch sunset, days will seem to lengthen from December 1-21 when they are in fact still getting shorter. 

George Observatory

Come see us Saturday nights at the George Observatory!  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. 

Clear Skies!

Do you have any astronomy questions or would like email updates on current events in the sky, at the planetarium, and at George Observatory?  If so, send us an email to astroinfo@hmns.org.

Geminid Meteor Shower offers a brilliant weekend at the George!

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

The Geminids are unique among meteor showers because they are associated not with a comet but with an asteroid, 3200 Phaethon. Comet orbits are so oblong that that they cross Earth’s orbit almost at right angles. For most meteor showers, then, Earth doesn’t rotate us to face the debris field until after midnight. The less oblong orbit of an asteroid meets Earth’s orbit at a shallower angle. Thus, we rotate to face into the debris field earlier in the night, even before midnight. With Geminids, then, we see significant activity as early as 9 or 10 p.m., although the shower will likely peak just before dawn.

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The Geminid meteor shower is one of the brightest, most active, and most remarkable annual stellar events.

A new moon falls on Thursday, Dec. 10 this year. That makes Sunday night’s moon a slender crescent which sets by 8 p.m. This should guarantee us nice, dark night for viewing once the shower gets going. The Geminid Meteor shower peaks every December and is one of the best, most reliable showers, producing an average of 100 meteors per hour.

They’re called the Geminids, by the way, because we see them seem to ‘radiate’ from an area of sky near Castor, a bright star in Gemini, the Twins. In December, Gemini is still rising at dusk, but it has cleared the horizon by 8 p.m., passes high overhead at about 1 a.m., and is in the west by dawn. Remember, though, that not all meteors will be in Gemini! They just seem to radiate from that direction, which means that wherever they appear, the streak will seem to move away from Gemini.

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Therefore, it’s best to lie on your back so you can observe as much of the sky as possible at once. Remember to have patience, as the 100 meteors per hour is about one or two per minute on average. One minute can be a long time if you waiting for something to happen.

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Weather permitting, telescopes, including the Gueymard Research Telescope, will be available for public use at the George Observatory until 10 p.m. during the Geminid Meteor Shower event.

As with all showers, the Geminid Meteor Shower will be best viewed away from city light pollution, weather permitting. The George Observatory will be open Sunday night until midnight for observation. For directions to The George, located just an hour southwest 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.

 

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!