The Pretty Crescent Moon Meets Morning Planets and Moves Over Mars and Inner Planets at Sunset!
The Moon and Planets ✨
This is the favorite week of the month for serious astronomers! The evenings between Sunday and next weekend will be the darkest all around the world because the moon will be completing the final week of its monthly trip around Earth. This is the period when the waning moon moves closer to the pre-dawn sun — so the moon rises between midnight and dawn, and then remains visible during morning daylight hours.
On Monday, the waning crescent moon will become visible in the southeastern sky after it rises at about 3 am in your local time zone — making a pretty sight as you head outside to walk the dog, or head to work or school.
The real treat occurs the next morning. In the southeastern morning sky on Tuesday, February 18, the waning crescent moon will cross in front of (or occult) the planet Mars for observers in North America (except western Canada & Alaska), most of Central America, the Caribbean, northern South America, the southern tip of Greenland, and the Azores. In the Eastern Time zone, the event will begin in daylight at 7:25 am EST when the bright, leading limb of the moon will first cover Mars. The planet will re-appear from behind the moon’s opposite, dark limb at 8:50 am. (The exact ingress and egress times vary depending on your location.) Use good binoculars or a backyard telescope to see the event — although your telescope will flip and/or invert the arrangement I described above. Observers located in the Central, Mountain, and Pacific time zones will get to see the encounter in a darker sky. Let me know if you see it!
On Wednesday morning, the pretty, crescent moon will hop east to sit a few finger widths to the right (or 4° to the celestial west) of the bright planet Jupiter. The pair will be visible quite low in the southeastern sky after they rise at about 5 am local time — until almost sunrise.
The fun continues on Thursday morning, when the moon will hop east again and land a few degrees to the lower right (or 2.5° to the celestial southwest) of dimmer Saturn. This meet-up will be harder to see because the pair will be even lower in the sky, and the sun will be preparing to rise after soon them. But have a go!
Because of how nearly-horizontal the morning ecliptic is at this time of year, Friday morning will offer a final opportunity to see the very slim crescent moon — two days before its new phase. That’s because, even though the moon will be positioned a generous 20 degrees away from the sun on Friday, it will be positioned to the right of the rising sun, rather than above it.
The moon will reach its new moon phase at 10:32 am EST (or 15:32 GMT for the rest of the world) on Sunday. At its new phase, the moon is travelling between the Earth and the sun. Since sunlight is only reaching the side of the moon aimed away from us, and the moon is in the same region of the sky as the sun, the moon is hidden from view for about a day.
As I described above, three bright planets are lined up in the eastern pre-day sky now — Mars, Jupiter, and Saturn. Over the next several weeks, they’ll put on a show as faster Mars slides close to and between the two gas giants. Stay tuned for updates on those spectacular meetings. For the moment, the three planets are well spaced apart — illustrating how the plane of our solar system spans the sky.
Mars will rise first; at about 4 am local time. The reddish planet is starting to increase in brightness because Earth is moving slowly towards it. Closest approach will occur in October — by which time Mars will be rising at sunset. The relative positions and combined orbital motions of Earth and Mars are causing Mars to appear in roughly the same place in the sky at the same time every morning. However, the planet is actually moving rapidly eastward in front of the distant background stars because they rise four minutes earlier every morning — while Mars does not. Mars will spend the next six weeks crossing the stars of Sagittarius (the Archer).
Sagittarius straddles the Milky Way. During mornings this week, the orbital motion of Mars will carry it close to several bright deep sky objects. On Monday, look for the Trifid Nebula (Messier 20) and the open star cluster Messier 21 sitting less than a finger’s width to the upper left (or 0.5° to the celestial north) of Mars. The Lagoon Nebula (Messier 8) will be positioned one finger’s width below Mars, making those objects easy to find in binoculars and backyard telescopes. Mars will also be sitting less than a palm’s width below a very bright clump of stars known as Messier 24, also known as the Sagittarius Star Cloud. There are lots and lots of star clusters and nebulas in the area!
Next in the morning planet parade is very bright Jupiter, which will be sitting 1.7 fist diameters to the lower left (or celestial east) of Mars. If your southeastern horizon is low and free of obstacles, try and spot Jupiter after it rises around 5 am local time.
Last in line, yellow-tinted Saturn will be situated quite low in the eastern pre-dawn sky — about a fist’s diameter to Jupiter’s lower left. This week the Ringed Planet will rise just before 6 am local time. Good news — every week from here on out, the two gas giants will rise earlier — placing them higher in the sky for your viewing pleasure! By summer, all three planets will be visible for your summer evening stargazing.
The two innermost planets are visible in the western evening sky. Mercury is completing its best evening appearance during 2020 for equatorial and Northern Hemisphere observers around the world — so we’ll only have this week to catch it. Tonight (Sunday) after sunset, Mercury will set at about 7:10 pm local time — making it relatively easy to pick out the speedy planet sitting a generous palm’s width above the west-southwestern horizon after sunset. The optimal viewing time for Mercury will fall between 6:15 pm and 6:30 pm in your local time zone. Mercury can be easily seen with unaided eyes in a cloud-free sky. If you use binoculars to hunt for Mercury, make sure that the sun has already completely sunk out of sight first.
That incredibly bright “star” that you’ve been seeing in the southwestern sky every evening recently is Venus, the Goddess of Love, or the “Evening Star”. She’ll gleam in the western evening sky until spring. This week, Venus will set in the west after 9:30 pm local time. If you want to see Venus’ less-than-fully-illuminated disk in your telescope, try to view it as soon as you can find it, while Venus is higher in the sky. That way you’ll be viewing the planet through less of Earth’s distorting atmosphere.
The only other observable evening planet is Uranus. The blue-green planet can be seen for a few hours after dusk (it sets at about 11:15 pm local time). Uranus is located a generous palm’s width above (or 7° to the celestial east of) the modest stars that form the V-shaped constellation of Pisces (the Fishes). To be more accurate, Uranus is actually located within the boundary of Aries (the Ram) — to the lower left (or to the celestial south of) that constellation’s two brightest stars, Sheratan (the lower, more westerly star) and Hamal (the higher, more easterly star). The planet is also a fist’s diameter to the right of the ring of stars that form the head of Cetus (the Sea-Monster).
Shining at magnitude 5.8, Uranus is bright enough to see under dark sky conditions with unaided eyes and with binoculars — or through small telescopes under less-dark conditions. If you view Uranus right after the sky darkens at about 7 pm, it will be higher — and you’ll be looking through the least amount of Earth’s disturbing atmosphere.
Astronomy Skylights for this week for the week of February 16th, 2020 by Chris Vaughan.
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