Moon Over Mars The biggest event for February is one most of us won’t see. The Moon slides in front of Mars on the morning of the 11th. Usually the Moon is a great pointer toward fainter objects. This occultation of Mars by the Moon occurs after Sunrise on the 11th. Will we be able to use the Moon, a thin crescent, to find Mars in the morning sunshine? I’ll have a separate post on this closer to the event.
Pop-Up Planetary Event Mercury strays into the evening sky in one of its best appearances of the year. Already out in the evening sky as the month begins, Mercury is low to the right of brilliant Venus. Venus, at magnitude -4.1, sets an example, soaring higher, enticing magnitude -1 Mercury to show itself after sunset at the beginning of the month. Mercury will only go 18 degrees out from the Sun, as compared to Venus’ 43 degrees. About 45 minutes after sunset, look toward the lower right of Venus, towards where the Sun had set, to spot the speedy messenger of the gods.
Mercury reaches greatest elongation from the Sun on the 11th. By then, at magnitude -0.3, it’s already only half as bright as in early February. Starting on the 22nd, Mercury is only visible in the Solar and Heliospheric Observatory’s C3 camera, shuttling well north of the Sun on its way to its next delivery in the morning sky in March. [Link to Naval Research Lab map of planets transiting through the C3 camera]
Venus is starting to look less round and more gibbous, 63%-lit by month’s end. Mercury’s phase decreases faster, half-lit by the 10th. Both Venus and Mercury appear larger than Mars. Venus is about Saturn’s size.
If you missed the Venus/Neptune conjunction in January, get a good star chart and try for Neptune near 4th magnitude Phi in Aquarius on the 10th, between Venus and Mercury. Uranus is up in the star-poor area between Aries, Pisces and Cetus all evening, starved for attention.
I haven’t seen Comet PANSTARRS C/2017 T2 yet, even though it’s up in our northern skies all night. In February, this magnitude +9 wisp of dust, rock and snow is going to hang just above Cassiopeia. T2 will be highest after sunset. Try for it with binoculars in a dark sky as it brightens until May.
[chart with panstarrs at midmonth]
Morning Sky Low Down In the meantime, the morning sky is hopping with Jupiter and Saturn straining to join Mars just before sunrise. They are strung out low in the southeast, as if groggy from being awakened so early in the morning. Mars is 55 degrees out from the Sun, with Jupiter and Saturn trailing at 36 and 26 degrees elongation, respectively. Look for magnitude
-1.9 Jupiter with Mars right ahead at magnitude +1.3 and Saturn left behind at magnitude +0.6.
Mars should be more colorful than the giants that trail it, but I haven’t been impressed that it looks really red yet. Mars will gain about a half magnitude per month until October, when it will be brilliant. Barring dust storms, the red planet should live up to its colorful reputation as it gets brighter.
Loony Facts If you have a clear southeastern horizon, follow the waning Moon as it checks off visiting Jupiter and Saturn on the 19th and 20th. The Moon reaches perigee on the 10th, just 30 hours after Full Moon. Perigee near a New or Full Moon date makes for higher than normal tides for a few days following the dates of Full Moon. The Full Moons for the next three months will be even closer than February’s.
The International Space Station’s visible overflights are in the evening through the 10th, and in the morning from the 19th.
February 29th marks Leap Year Day, an extra day that keeps the calendar aligned with celestial milestones during our annual trips around the Sun. The last year that was evenly divisible by four but was without a Leap Year Day was 1900. Years divisible by 100 aren’t leap years, unless they are divisible by 400, like 2000 was. These exceptions are built into the Gregorian Calendar rules to keep our calendar even more precisely in sync with the stars. A bit more about this in a few days.