2021, January 29: Moon Blocks Star

2021, January 29: The bright moon appears near Eta Leonis (η Leo) in the eastern sky later during the evening.

January 29, 2021:  The moon blocks the star Eta Leonis from parts of the Western Hemisphere during the early evening.

by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 7:06 a.m. CST; Sunset, 5:03 p.m. CST.  Check local sources for sunrise and sunset times for your location.

The moon covers a bright star in Leo this evening as seen from the southern tier of U.S. states, Mexico, Central America, and northern South America.

The star, Eta Leonis (η Leo on the chart), is covered or occulted by the moon. (The chart is made for the Chicago, Illinois region.) The event begins in the Eastern Time Zone at around 10 p.m. EST.  The moon slowly inches in front of and covers the star. Depending on your location, the occultation could occur over a few minutes or longer than an hour.

For those in the northern U.S. and Canada, the moon appears very close to the star.  The pair will be a pretty sight.

Eta Leonis is a relatively bright star – not as bright as the famously-named stars – easily seen in the “Sickle of Leo” above Regulus without a telescope or binocular.

The moon rises about an hour after sunset in the east-northeast.  The moon appears near the star.  By the time the moon begins to cover the star, about 4 hours after sunset, the lunar orb is about one-third of the way up in the eastern sky.

For those who are in the region where the occultation occurs, the event is relatively slow-moving.  Use a spotting scope to watch the moon initially move in to cover the star.

While the star is easy to see, the bright moon that is 99% illuminated can overwhelm the local starfield with its visual intensity.

For specific details about starting time and ending time your location, see this link.  The times on the site are in Universal Time.  Subtract 5 hours for Eastern Time, 6 hours for Central Time, 7 hours for Mountain Time, and 8 hours for Pacific Time.

Read about Mars during January.

Detailed Note: One hour before sunrise, the bright moon (16.3d, 99%) is over 19° in altitude in the west.  It is 12° to the lower right of Regulus.  In the evening, about 30 minutes after sunset, Mercury is less than 10° in altitude in the west-southwest.  As the sky darkens further, Mars is over 64° in altitude above the southern horizon, west of the meridian.  In the starfield, use a binocular to observe the Red Planet 2.8° to the upper right of ο Ari, 4.5° to the upper right of σ Ari, and 3.9° to the lower right of π Ari.  Two hours after sunset, the bright moon (16.8d, 98%) is less than 10° in altitude above the east-northeast horizon.  In a few hours, the moon occults Eta Leonis (η Leo, m = 3.5), the star above Regulus in the Sickle of Leo, from the southern tier of the U.S., Mexico, Central America, and northern South America.  Begin looking before 9 p.m. CST.  The star is to the immediate left of the bright moon.  If you live in the region of visibility or you are traveling the details to observe the occultation are here: http://www.lunar-occultations.com/iota/iotandx.htm

Read more about the planets during January.

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