The evening southwestern horizon

If skies are clear this week, there are three planets visible in our southwestern evening sky. As it has been doing all month, Venus climbs higher and becomes brighter. Jupiter has dropped closer to the horizon and tiny Mercury pushes slightly higher than Jupiter.

Tonight, the thin crescent moon sits just above the Jupiter - Mercury duo. Binoculars help give a better view.
By New Year's Eve, the moon moves next to Venus, giving a striking combination.

Such is our view from Earth ...

Astronomically, winter is here

Today the Earth reaches the point in its orbit where its polar axis reaches its most extreme angle with respect to the position of the sun. Our planet's north pole is tilted at its greatest angle away from the sun, and our south pole is tilted at its greatest angle towards the sun. In other words, it is the first day of winter in the northern hemisphere and the first day of summer in the southern hemisphere.

Also, the time that the sun is above the horizon is the least for the next 365 days, being 9 hours 36 minutes for Roanoke. Compare this with the time on the first day of summer which is 14 hours 44 minutes.

Such is our view on Earth ...

Line Up

Four planets and the Sun arrange themselves in a line up this week. Mars, on the far side of its orbit, is situated behind the Sun and so is Mercury. Because they appear close to the Sun, they can not be seen. Jupiter sets about 7:45 p.m. and can be found in the southwest 30 minutes after sunset. Venus, quite a bit brighter than Jupiter, follows it to the horizon setting around 8:00 p.m.

This time every year the Sun is located not in a familiar constellation of the zodiac, but a relatively unknown one, Ophiuchus. It drifts eastward through it until December 18 when it crosses the border into Sagittarius.

The final "bright" planet, Saturn, rises in the east about 11:45 p.m. in Leo. By dawn, it is high in the south. The 3rd quarter Moon is close to it on the 18th and 19th.

Such is our view from Earth ...

Position of Jupiter and Venus

From our point of view on Earth, Venus and Jupiter have appeared near each other over the past couple of weeks. Jupiter happens to lie almost on the ecliptic, which is the plane of the Earth's orbit projected onto the celestial sphere. Venus is a couple of degrees below it.

Monday evening's close triple conjunction had the Moon also 2º below the ecliptic. About 1 pm on that day, the Moon occulted Venus, ie., it appeared to move in front of it. It was daytime here in Virginia, but it was early evening in London. They must have had a spectacular sight!

Such is our view from Earth ...

Best Celestial Sight of 2008

The early evening sky on December 1st holds something special. Jupiter and Venus are approaching each other and will be at their closest separation on that date. It is made even more remarkable by the addition of the thin crescent Moon, full with Earthshine. These three bodies in our solar system fit in the same field of view of a pair of binoculars giving a spectacular arrangement.

Even though they look like they are right next to one another, they are nowhere near each other in space. The Moon glows 250,000 miles away, while Venus and Jupiter respectively lie 93,000,000 and 540,000,000 miles from Virginia.

This all adds up to be the prettiest celestial sight of the year. Look to the southwest between 5:30 and 7:15 p.m. and you won't be disappointed!

Venus rises to greet Jupiter

The two brightest planets in our evening sky are getting together. Venus rises higher each night approaching Jupiter in the southwestern sky. They are next to each other on December 1. Don't miss viewing them over the next few nights, if the weather permits!

Such is our view from Earth ...

For a good view of the International Space Station and Space Shuttle Endeavor ...

On Thursday and Saturday evenings, people in the Roanoke area have good opportunities to see the International Space Station with the Space Shuttle Endeavor docked to it as they pass directly overhead. They will appear together as a single bright star, growing to the brightness of Jupiter, which lies in the southwest as darkness falls.

At about 6:12 p.m. on Thursday, look to the southwest just to the right of bright Jupiter and brilliant Venus. The station-shuttle pair appears as a star moving upwards in the sky. It takes three minutes to advance overhead, brightening all the while. Another minute passes before they disappear in the Earth's shadow high in the northeast.

The pair appears again on Saturday evening, this time beginning at 5:30 p.m in a brighter sky. Look to the upper right of Venus and Jupiter for this moving pair which appears as one starlike object. By 5:32, it is directly overhead, and three minutes later, it disappears from view as it enter the Earth's shadow.

When they are overhead, the pair are at their closest to us, some 225 miles above our heads.

Such is our view from Earth ...