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Venus dominates the evening sky

Donald G. Luttermoser • Jan 28, 2017 at 11:23 PM

Brilliant Venus continues to dominate the evening sky in February and reaches greatest brightness this month on the 16th.

Indeed, sharp-eyed observers might be able to spot this brightest planet during daylight hours with the naked eye. After sunset in a moonless sky, Venus is bright enough to cast shadows, especially if there is snow on the ground.

Venus continues its northward journey on the sky, setting some 3¾ hours after the sun at the beginning of the month. By month’s end, Venus-set occurs 2¾ hours after sunset. Through a telescope, the crescent of Venus thins from 40 percent to 18 percent lit, whereas its angular size grows larger and larger, making for impressive viewing through a telescope.

By the end of the month, one should be able to make out the crescent shape through low-power binoculars.

Just to the upper-left of Venus is the red planet Mars. The separation on the sky between these two planets is at minimum on Feb. 1 at 5.4 degrees. Following this date, the separation between these two planets begins to increase as the motion of Venus swings back toward the sun.

The brightness of Mars continues to fade as the faster-moving earth pulls away from the red planet. On Feb. 26, Mars passes just 0.6 degrees north-northwest of planet Uranus – one will need binoculars to spot faint Uranus.

The next planet to rise during the night is Jupiter, which comes up around 11 p.m. as February opens. Jupiter will be just to the northeast of the bright star Spica in the constellation of Virgo. This king of the planets continues to brighten throughout the month as it approaches opposition on April 7. By the end of February, Jupiter rises around 9 p.m.

In the early morning sky, Saturn rises about three hours before sunrise in the southeast sky as February opens. The red supergiant Antares can be seen to Saturn’s left, both hanging in the southeastern sky at the same altitude.

During the first half of February, Mercury sits very low in the southeast sky ¾ of an hour before sunrise, which unfortunately will make it difficult to spot in the bright morning twilight.

The moon will be at full phase on Feb. 10 at 7:44 p.m. However, this full moon will partially fall into the earth’s shadow producing a deep penumbral lunar eclipse. From the moon’s perspective, a lunar penumbral eclipse occurs when the sun is partially eclipsed by the earth.

This penumbral eclipse starts at 6:14 p.m. and concludes at 9:14 p.m. During this time period, viewers should clearly see the moon dimming as it approaches mid-eclipse at 7:44 p.m., then begin to brighten until the eclipse ends.

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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