"Tonight's Sky" is written by retired planetarium director Dave Leake and reprinted with his permission. See Dave Leake's Prairie Skies column in the Champaign–Urbana News-Gazette each Sunday. Dave Leake's preview of 2021 sky events can be found here.
April 25 – May 1
Tomorrow’s full Moon is called the “Pink Moon.” Not that the Moon is pink, but some of the first flowers you may see in the fields are pink. It’s also a “supermoon,” which elevates my blood pressure. Yes, the Moon is closest to us on Tuesday but the difference between close and average is a paltry 6%. Point being, the human eye can’t really detect that the Moon looks larger. Now if the Moon appears larger as it rises, it’s an optical illusion. Extend your pinky finger at arm’s length and attempt to cover the Moon. I think you’ll be surprised how easy it is! Don’t worry about supermoons – just enjoy the extra light at night from our neighbor in space.
The month of May should give us the best evening views of the elusive planet Mercury for all of 2021. Start looking this week, near the west-northwestern horizon. Tomorrow night, use binoculars and see if you can see Mercury above a brighter planet Venus and below the Pleiades star cluster. Tuesday night, Mercury is just to the left of the Pleiades. Keep watching as Mercury will be higher in the sky each evening.
Tuesday evening through Thursday morning is the peak of the Eta Aquarid meteor shower. Earth crosses the orbit of Halley’s Comet at this time and the dust we encounter can produce a glowing track in the sky. Expect around 10 meteors an hour.
A “new” Moon Tuesday means the Moon will reenter the evening sky at mid-week. You can also use the Moon to locate the other inner planets of our solar system. Though a challenge for skywatchers, a thin crescent Moon will be only a degree from Venus on Wednesday evening right after sunset in the west-northwest. This will be the closest the pair will be all year, but you’ll need to see down to the horizon. Thursday night, the Moon is just left of Mercury. And Saturday the Moon is just to the right of Mars!
At Thursday night's CU Astronomical Society meeting, Jim Wehmer will discuss stellar streams. Join us on Zoom by visiting cuas.org for the link.
I hope you have been watching the planet Mercury in the west after sunset. This is your best view of this planet in the evening for the year. Tomorrow night, Mercury reaches its greatest separation from the Sun and won’t set until nearly 10 pm. Look for it beneath the “horn” star of Taurus, the Bull.
If you’re looking in the evening twilight this week, peer to the southwest and say “goodbye” to the brilliant star Sirius. Sirius is considered a winter star and will soon be enveloped by the glare of the Sun. Don’t fret; we’ll see it again this fall. Wednesday’s first quarter Moon sits above Regulus, the heart of Leo, the Lion.
Wednesday’s full Moon is the “flower” or “corn-planting” moon for obvious reasons. It’s also a supermoon, but if you’ve read this column you know how I feel about those! It’s also time for a lunar eclipse, but don’t get your hopes up. The eclipse favors the west coast, but we might see a little bit of it if you get up early. You’ll need to look low in the southwest Wednesday morning as the eclipse begins at 4:55am but the sunrise at 5:28am will prevent us from seeing the entire event.
Friday evening, Mercury passes Venus on its way back towards the Sun, the pair coming to less than a half degree. Look low in the northwest just after sunset.
May 30–June 5
Tomorrow morning, early risers will see a nearly third quarter Moon below Saturn and then below Jupiter the next morning. This pair of planets won’t rise until after 1:30am this week but that will get earlier as we go through the summer.
If you’re more of an evening person, look nearly straight up after sunset and see if you can find the familiar Big Dipper. The Dipper can be seen year-round though it is highest in our sky in the evenings in spring. If you’re facing north while watching it will look upside down! Follow the curve made by the handle stars to the east to the orange star Arcturus, the fourth brightest star in the sky.