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Mars and Neptune to have close conjunction

Donald G. Luttermoser • Dec 23, 2016 at 8:42 PM

Venus continues to dominate the evening sky and reaches greatest elongation from the sun on Jan. 12.

Venus gains in altitude in the southwest sky as it moves northward along the ecliptic during the month. In addition, Venus is near maximum brightness by the end of January.

As the month progresses, Venus continues to move closer and closer to Mars on the sky. By the end of the month, these two planets will only be about 5 degrees apart from each other.

For those of you with binoculars, look at Mars on New Year’s Eve — on that evening, planet Neptune will be extremely close to Mars on the sky. Since Neptune will be 20 times farther away from us than Mars, Neptune will be 250 times fainter than Mars during this close conjunction.

Twelve days later on Jan. 12, Venus passes within half a degree from Neptune. The brightness of Mars over January continues to diminish to where it will be nearly 20 times fainter in January as compared to its brightness last May at opposition. However, Mars will still be the second brightest celestial object in this part of the sky outside of Venus.

We now need to wait until just after midnight to catch a glimpse of the next bright planet to rise — the king of the planets, Jupiter. It continues to slowly brighten as it approaches its opposition this April.

During 2017, Jupiter will be just to the northeast of the bright star Spica in the constellation of Virgo. As a matter of fact, Jupiter will have three different conjunctions with this star during this year with the first occurring on Jan. 20.

To see the remaining naked-eye planets, we have to wait until just before dawn to catch Saturn and Mercury. At the beginning of the month, Saturn rises about an hour before sunrise in the southeast sky, and by month’s end, it rises three hours before the sun.

During the second two weeks of January, Mercury can be spotted to the lower left of Saturn. Unfortunately, Mercury will be very low in the sky during this morning apparition, which will make it difficult to spot in the morning twilight.

The earth is at perihelion, the closest to the sun in space, at 9:17 a.m. January 4. At this time, we will be 91,404,322 miles from our star, which is 3.1 million miles closer than when it is at its farthest point in July.

The waxing crescent moon will be to the lower right of Venus on New Year’s Day. On the following day, the moon will be halfway between Mars and Venus. On Jan. 3, the crescent moon will be to the upper left of Mars. Then during the last two days of the month, the moon once again passes by Venus and Mars, though this time it will pass just below these two planets.

The full moon in January occurs on the 12th at 6:35 a.m. Native Americans often called the January full moon the Full Wolf Moon since wolf packs howled hungrily outside of their villages.

The next free public astronomy open house at the ETSU Powell Observatory will occur on Saturday, Feb. 4 from 8-10 p.m. At these open houses, the public can view objects in the sky through telescopes and hear talks by faculty of the Physics and Astronomy Department. Note that the open houses are cancelled if the sky is cloudy.

Make sure you dress warmly since you will be standing outside to look through our telescopes. Further information about these open houses and directions to the observatory can be found on the web at www.etsu.edu/cas/physics/observatory/default.aspx.

This month’s Night Sky was written by Donald G. Luttermoser, chairman of the Department of Physics and Astronomy at ETSU. He can be reached at lutter@mail.etsu.edu. Any students wishing to pursue a career in Physics or Astronomy are encouraged to contact him at this email address. Astronomy-related information for the public, including a link to the ETSU Powell Observatory, can be found at www.etsu.edu/cas/physics by selecting the Public Outreach pull-down menu at the top of that web page.

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