2023, February 5: Snow Moon, Venus, Jupiter, Mars Evening

February 5, 2023: The micro-Snow moon is in the sky all night.  Three bright planets – Venus, Jupiter, and Mars are visible after sundown.

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by Jeffrey L. Hunt

Chicago, Illinois:  Sunrise, 6:59 a.m. CST; Sunset, 5:11 p.m. CST.  Check local sources for sunrise and sunset times for your location.  Times are calculated from the U.S. Naval Observatory’s MICA computer program.

Jupiter’s Great Red Spot’s transit times, when it is in the center of the planet in the southern hemisphere: 4:31 UT, 14:26 UT; Feb. 6, 0:22 UT. Convert the time to your time zone. In the US, subtract five hours for EST, six hours for CST, and so on.  Use a telescope to see the spot.  Times are from Sky & Telescope magazine.

This month’s Full moon – also known as the Snow moon – occurs today at 12:29 p.m. CST.  This is the smallest Full moon of the year. 

Earth’s orbit is elliptical and not a circle.  The closest point to Earth is known as perigee and farthest from our planet is apogee.  The distance varies about 14%, from the so-called supermoon and today’s micro-moon.

The popular press regularly features the supermoon, when in reality the moon’s size changes 14% from apogee to perigee.  The two circles above are different by 14%.  Can you tell which is bigger?

Every Full moon appears “big and bright” in the sky.  There’s hardly any difference in the size and brightness from the variations in distance during the year.  Surely any popular reminder to get us outside to look up is helpful.  There are other celestial events that are easier to see than the variability of the moon’s size.

The upcoming Venus-Jupiter conjunction is one of the highlights of the observing year.

Here is today’s planet forecast:

Morning Sky

An hour before sunrise, the bright moon, 100% illuminated and about six hours before the official Full moon phase, is about 15° up in the west-northwest.  At this altitude – height above the horizon – the lunar orb’s light casts long shadows of the terrestrial features.

Regulus – the brightest star in Leo – is nearly 20° up in the west and 18° to the upper left of the moon.

For most observers, Mercury is impossible to see.  It is still west of the sun, meaning that it rises before sunrise.  The time difference today is seventy-four minutes. The planet loses two minutes of rising time each day as it moves toward its superior conjunction, then its best evening appearance of the year.  Nearly thirty-five minutes later, the solar system’s fastest-moving planet is less than 7° up in the southeast, but bright twilight overwhelms most celestial sights in that region of the sky.

Evening Sky

Three bright planets – Venus, Jupiter, and Mars – are visible after sundown.  Saturn left the western sky after sunset last month after the conjunction with Venus.  This evening Saturn sets about 40 minutes after sundown.  The Ringed Wonder appears to pass behind the sun on the 16^th, beginning a slow climb into morning twilight.  It makes its first morning appearance around the time of the equinox.

At forty-five minutes after the sun sets, brilliant Venus is about 15° above the west-southwest horizon.  Jupiter is less than halfway up in the southwest and nearly 25° to the upper left of Venus. 

Venus is moving eastward faster on the celestial sphere compared to Jupiter.  The Evening Star overtakes and passes the Jovian Giant on March 1^st.  Until then, each night the gap closes by about 1°.

Jupiter moves into Cetus tonight.  The Sea Monster’s boundary with Pisces is very close to the plane of the solar system.  On occasions, the planets and moon appear briefly in front of this constellation. Jupiter is in front of Cetus through the 18^th.

Beginning on the 20^th, the Venus-Jupiter separation is less than 10°.  That is about the distance from the thumb to pinky finger on your fist at arm’s length.

Unlike looking for the difference in the size of a micro-moon and a supermoon, a Venus-Jupiter conjunction is a spectacular sight, the two brightest starlike bodies are close together in the evening sky.  While not a rare event, their conjunction is one of the year’s celestial highlights.

Farther eastward, the Snow moon is about 8° above the east-northeast horizon.  The moon is in the sky all night as Earth rotates.  It is south around midnight and in the western sky tomorrow morning. The ground is bright enough for a night walk without a flashlight.

Mars is higher in the southeast, 8.2° to the upper left of Aldebaran, the brightest star in Taurus.  The Red Planet is marching eastward toward a conjunction with Elnath, the Bull’s northern horn, on March 9^th.

For sky watchers with telescopes, Jupiter’s Great Red Spot is in the center of the planet in the southern hemisphere at 6:22 p.m. CST.  The planet spins about every ten hours bringing the long-lived storm into view.  With Jupiter appearing lower in the southwest after sundown, the window to see the spot is closing for this apparition of the planet.

Jupiter’s large moon Callisto is reaching its greatest separation from the planet.  With a binocular look for the four largest moons in a line from Jupiter’s upper left to lower right.  They appear starlike through the binocular.  Callisto is farthest from Jupiter, to the lower right.

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