by William J. Bechaver
EARTH — The Winter Solstice occurs this week, with the longest night of the year, we have a great opportunity for star gazing and planet watching.
Last week, we used the moon to find fading Saturn in our evening sky. Both Saturn and Jupiter are further away than they were last week. But gigantic Jupiter is always brilliant in the night sky, and can hardly be confused with anything else, even at its most distant.
Jupiter is the largest planet in the solar system, and currently at less than half the distance of Saturn. But this week, the moon moves to be near Jupiter, and the pairing will be close enough to make it a beautiful sight in our night sky.
As the sky darkens on Thursday December 21, the moon will be above brilliant Jupiter, high in the eastern sky. Look early, and as the sky darkens after sunset, you will see Jupiter emerge from the darkness.
As the pair traverses the sky during the greater part of the night, they will draw closer together. Jupiter sets just a few hours after midnight, now. The pair will be just over three degrees apart at their setting, the moon setting less than ten minutes before Jupiter disappears over the western horizon.
As the moon makes its way across the sky during the course of a month, its phases change as it encounters each planet as it passes through its cycle. But this is its last visible planetary encounter of the year, as it won’t traverse the sky to join Venus until more than a week into the New Year.
This week, the asteroid Vesta will be at its closest position to Earth. Vesta is an asteroid in the belt of asteroids that occupy the space between Mars and Jupiter. More accurately, Vesta is a family of asteroids that number over 30,000 individual bodies.
But these asteroids pose no threat to Earth. Their orbits maintain a distance further than Mars. And though Vesta is at its closest position to Earth, and is in fact, closer than Mars right now, it is not the closest of the major asteroid belt bodies to us. Lutetia is another major body in the asteroid belt, and it is four million miles nearer to Earth right now. Mars, on the far side of its orbit, on the far side of the sun, is nearly ninety million miles further than the closest of the large belt asteroids right now.
Mercury is on its journey past Earth right now, passing between Earth and the sun. It will pass between on the afternoon of Friday 22 December. It appears too near the sun to view from Earth right now. But by next weekend, it will be entering the morning sky, not quite visible before sunrise.
Mars is just emerging from the morning glare into the eastern sky. And as Mercury passes Earth, it will begin to draw further away. Venus is also moving further from Earth in its shorter orbit. In fact, right now, Mars is the only planet that Earth is moving toward, as we are slowly drawing further from Jupiter and Saturn in their outer orbits, as we begin to gain slowly on Mars.
The weather posed a slight problem for the display of the Geminid Meteor Shower. But the icy and foggy conditions moved out of most of our viewing area just in time to catch the peak of the rocky meteor display, though our peak rate was reduced by hazy skies. The more brilliant fireballs were spectacular to behold as they blazed their way across our dark night skies.
Continue watching this week for the trailers at the end of the Geminid Meteor Shower, for even though the peak of activity has passed, the shower will remain active for another week.
So, with a little luck, we will have clear skies to see the passage of the moon with Jupiter on Thursday night, one of the longest nights of the year, as we are just past the solstice, and looking forward to longer days.
With our dark skies here, they only need to be clear, so keep your eyes on the skies from sunset to sunrise.
Thanks for the positive feedback about our featured columns, and your continued interest in astronomy. If you have any questions or article requests, contact us at spacescape@rocketmail.com, or follow us on Twitter @ColoSpacEScapE for updates and additional viewing opportunities.
Astronomical times and distances of naked-eye objects for this weekend:
Sun Set = 4:45 p.m.
3 minutes later than last week
91.431 million miles from Earth
52,380 miles nearer than last week
3.074 million miles nearer than its furthest in July
Saturn Set = 9:34 p.m.
25 minutes earlier than last week
946.624 million miles from Earth
9,688,397 miles further than last week
132.045 million miles further than its nearest in August
Jupiter Set = 2:43 a.m.
28 minutes earlier than last week
406.127 million miles from Earth
8,371,737 miles further than last week
35.803 million miles further than its nearest in November
Venus Rise = 4:02 a.m.
14 minutes later than last week
105.474 million miles from Earth
4,281,493 miles further than last week
78.636 million miles further than its nearest in August
Moon Set = 5:00 a.m.
69 minutes later than last night
237,132 miles from Earth
1,816 miles further than last night
8,524 miles further than last week
Nearest is 221,557 miles
Furthest is 252,665 miles
Mars Rise = 6:24 a.m.
4 minutes earlier than last week
44 minutes before the sun
227.334 million miles from Earth
1,782,347 miles nearer than last week
9.650 million miles nearer than its furthest in October
Mercury Rise = 6:42 a.m.
71 minutes earlier than last week
26 minutes before the sun
63.177 million miles from Earth
4,918,479 miles nearer than last week
70.135 million miles nearer than its furthest in October
Sun Rise = 7:08 a.m.
3 minutes later than last week
91.428 million miles from Earth
3,302 miles nearer than last night
50,346 miles nearer than last week
3,077,873 miles nearer than its furthest in July
Full moon occurs on Tuesday, December 26th, at 5:33 p.m. We’ve lost 20 seconds of daylight since last week, and 22 minutes since last month, and a full five hours five minutes since the June Solstice. Our nearest planetary neighbor currently is Mercury.
Note: Times are local Mountain Time. Actual “sundown” is about a dozen minutes earlier than calculated “sunset”. Along the front range, differing times vary depending on your distance from the mountains.
William J. Bechaver is the director of SPACE • Spanish Peaks Amateur Cosmos Enthusiasts, the premier Astronomical Society for Southern Colorado and Northern New Mexico.
