The Full May Milk Moon washes out Comets and Meteors, while Jupiter Sports Spots!

Star Walk
5 min readMay 10, 2017

Binocular Comet Update

The comets I’ve been mentioning recently are still observable in binoculars and low power telescopes, although the moon will hamper things this week. Expect the comets to appear as faint greenish blobs (quite different from a star). If a comet develops a tail, it will point roughly away from the Sun.

Comet 41P/Tuttle-Giacobini-Kresak is an all-night comet visible as soon as it’s fully dark, but highest in the sky before dawn. It has peaked in brightness, but is still visible in binoculars. This week, the comet is in the eastern evening sky, to the lower right of the bright star Vega. It’s dropping lower, increasing the distance to Vega from 6° to 10° over the week. Keep an eye on it — this comet has a reputation for sudden outbursts that dramatically brighten it.

Comet 41P/Tuttle-Giacobini-Kresak in Star Walk 2 app.

Comet C/2015 ER61 (PANSTARRS) is a pre-dawn comet in the eastern sky that is moving eastward (towards the left) through the western fish in Pisces (the Fishes), in the region of sky just to the upper right of Venus. It rises about 3:30 am local time. It has only recently brightened past its expected peak.

Comet C/2015 V2 (Johnson) is an all-night comet that is still brightening. This week, it is moving southwest, from the top of Hercules in a direction towards the bright star Arcturus. Look above the eastern horizon in mid-evening, and nearly overhead in the wee hours. Being near the pole star, this comet stays up all night.

I posted finder charts for the comets’ paths during May here.

Eta Aquariid Meteor Shower

The annual Eta Aquariid Meteor Shower peaked before dawn this morning, and will taper off through May 26th — so continue to keep an eye out this week for these fast meteors with persistent trails, and a few fireballs. The source of the shower is material that has been shed during repeated passages of Halley’s Comet. Unfortunately, the moon is nearing full now, leaving the sky less than ideal. I posted a diagram here.

The Moon and Planets

Tonight (Sunday, May 7), Jupiter and the nearly full moon, plus the bright star Spica will make a nice sight together. The moon, with Jupiter only two finger widths to its right, will fit within a binocular field of view and make a nice photo opportunity. Look in the eastern sky after sunset. Then the three objects will cross the night sky together and be visible low in the western sky until about 4:30 am local time.

The May full moon, known as the “Full Milk Moon”, “Full Flower Moon”, or “Full Corn Planting Moon” (all traditional names that reflect Mother Nature’s stirrings this time of year) occurs Wednesday afternoon. This full moon always shines in or near the stars of Libra (the Scales), however the constellation is so dim that the bright moon will wash out those stars.

In the small hours of Saturday, May 13, the waning gibbous moon will sit 7° to the upper right of Saturn in the southeastern sky. The pair will move above the southern horizon by dawn. The following day, the moon will jump to sit 4° to Saturn’s left.

Earth and Moon in Solar Walk 2 app.

During the course of this week, Mercury becomes more easily visible in the eastern morning sky. Every morning, it shifts farther west from the Sun (but moving southward in the sky) while the spring Ecliptic tilts higher — both effects combining to make Mercury rise earlier than the Sun. Towards the end of the week, the best time to hunt is around 5:30 am local time. Search about 20° (two fist diameters) south of the where the Sun will rise.

Venus continues to blaze away in the eastern morning sky. This week, it rises about 4:15 am local time and can still be seen until sunrise. In a telescope, Venus is showing a waxing crescent phase. Yellowish Saturn rises about 11:30 pm local time this week, and remains visible until dawn, when it’s two fist diameters above the southern horizon. This month, Saturn experiences its summer solstice, the beginning of its summer. At this time, its axis of rotation tilts the maximum amount towards the Sun, causing its rings to be particularly wide open as viewed from Earth. Saturn’s axial tilt of 26.73° is similar to Earth’s 23.5° — so it experiences spring, summer, fall, and winter, too. But Saturn’s seasons each last almost 7.5 years!

Bright, white Jupiter is now an outstretched fist diameter to the upper right of Virgo’s (the Maiden) brightest star Spica. This week, the planet shines in the southeastern evening sky after dusk, reaches its highest point over the southern horizon at 11 pm, and sets in the west before dawn.

Jupiter and its four large Galilean moons are easily visible in a small telescope. A slightly larger telescope will also show the Great Red Spot and the round black shadows cast by Jupiter’s moons when they cross (or transit) the planet. Here are the best events in Eastern Daylight Savings Time. (Simply add or subtract the appropriate hours to convert them to your time zone.)

On Thursday, May 11, from 9:59 to 10:05 pm, the shadows of Io and Europa will briefly cross Jupiter simultaneously. Europa’s shadow will lead the way, already in transit as the sky darkens. At 9:59 pm Io’s shadow joins it for about 7 minutes, with the two shadows on opposite sides of the planet. After the first shadow departs at 10:05 pm, Io’s shadow continues alone until about 12:08 am. An even better double shadow transit occurs next Thursday, May 18.

The Great Red Spot is visible on Jupiter for about three hours centred on Monday, May 8 at 11:28 pm, on Thursday, May 11 at both 1:07 am and 8:58 pm (in twilight), and on Saturday, May 13 at 10:37 pm.

Jupiter’s Great Red Spot in Solar Walk 2 app.

Dim, reddish Mars, sitting about a palm’s width to the upper right of the bright orange star Aldebaran in Taurus (the Bull), is gradually sinking into the evening twilight, sets about 10:30 pm local time this week. While similar in appearance, the distant star will outshine the red planet. I’ll post diagrams for the morning and evening planets here.

Stargazing News for this week (from May 7th) by Chris Vaughan.



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