Evening planets: Mercury, Venus, Mars and a super Flower Moon viewing
The first two weeks of May offers several evening events. Tomorrow night and May 4, watch Mercury sail beside the Pleiades star cluster in Taurus.
Look very low toward the west-northwest horizon as twilight just begins to fade (about 9 p.m.) to spot a bright star. That’s Mercury. Grab your binoculars and sweep about 3 degrees to the right of Mercury to spot the Pleaides. A week later, Venus travels a bit more to the left of the Pleiades.
Each night, watch as pokey Venus and swift Mercury climb a bit further from the setting sun. An ultra-razor-thin crescent moon visits Venus on May 12. This gathering is difficult to spot since it occurs very low near the west-northwest horizon. Spotting Venus will lead the way to seeing the skinny crescent moon just a moon width to the left of our sister world.
The next night, May 13, a slightly fatter crescent moon will be much easier to spy more than 2 degrees to the left of Mercury. On May 15, the waxing crescent moon appears to have a close encounter with Mars. Look toward the west to spot the bright crescent moon as the sky darkens, around 9:30 p.m. Glance to the left of the moon to spot a modest reddish star. That’s Mars.
Watch the moon slowly creep toward Mars over the next hour. The moon closes from over 1 degree separation to less than 45 arc minutes just before setting.
May will be the best chance to observe Mercury in the evening sky this year. Naked eye observers will easily notice a steady climb to a maximum elevation on May 16, as well as a tenfold decrease in apparent magnitude or brightness as the month progresses.
Telescope observers will be treated to rapidly changing phases of Mercury. Tonight, Mercury will appear as a tiny 6 arcsecond dot about ¾ illuminated. Each week, Mercury will appear to grow slightly larger and display phases like the moon. On May 9, Mercury will look like a tiny half-moon. By mid-month, Mercury will show a fat crescent and appear about 1/3 larger. After May 20, Mercury will begin a rapid descent toward the setting sun.
If you have a very good west-northwest horizon, watch the last week of May as Mercury’s crescent phases shrinks from a quarter to a slender crescent. You may also be able to watch a close conjunction on May 28 as Venus climbs and Mercury sinks. First, find bright Venus then sweep with your binoculars or scope to the left less than a moon-width to spot dim Mercury.
On the night of May 25/26, the May Flower Full Moon will be near perigee — or closest to the earth. This is the second supermoon of 2021. The moon will be the closest to the earth at about 7 p.m. However, moon-rise on May 25 is about 8:10 p.m. Best views of the May Flower supermoon will be as the moon climbs above the east-southeast horizon. The moon will appear about 8% larger and nearly 15% brighter than average full moons. Enjoy.
Pre-Dawn: Meteor Shower, Jupiter, Saturn, Neptune, super flower total lunar eclipse
Predawn May skies host two major events.
First, on the morning of May 5 the earth plows through an ancient dust debris trail from Comet Halley. This is the annual Eta Aquariids Meteor Shower. These swift moving (144,000 mph) comet dust particles will light up the early morning skies from 3:30 a.m. until sunrise. Best counts of about 15 meteors per hour will be from 4-4:30 a.m. A moderately bright waning crescent moon will interfere after 4:30 a.m.
The second and most spectacular predawn event is a rare supermoon total lunar eclipse of the Flower supermoon on May 25/26. The partial lunar eclipse starts about 2:45 a.m. May 26 and takes nearly 90 minutes to reach totality at 4:11 a.m.
The total “blood moon” only lasts about 15 minutes as the second partial starts at 4:26 a.m. The sun rises on May 26 at 5:39 a.m. as the full moon sets at 5:49 a.m. before the second partial finishes.
The moon barely travels through the top of the deep umbral Earth’s shadow explaining the brevity of totality. It also results in a brighter and lighter north part with a darker and redder south part at maximum totality at 4:19 a.m.
The next total lunar eclipse occurs on the evening of May 15, 2022 but only part of the eclipse is seen at moonrise. To see a complete total lunar eclipse, we will require waiting until the predawn hours of Nov. 8, 2022.
As you watch the moon slip slowly into the earth’s shadow, turn your telescope to the southeast to spot Saturn, Jupiter and Neptune. All are well placed for observing during the eclipse. You can also enjoy these planets while waiting for the Eta Aquariids on May 5.
Umpqua Astronomers Meeting
Umpqua Astronomers and the interested public can join a virtual meeting monthly on Zoom. The meeting time is 7 p.m. on May 11.