New Moon near Mercury and Mars, Crescent Moon near the Beehive, and the Big Dipper is a Sky Tool!

The Moon and Planets

The moon will be at its New Moon Phase, passing between the Earth and the sun, tomorrow (Monday) morning. That leaves it absent from the night time sky tonight and tomorrow. If you have clear skies in Sunday night, grab your binoculars and telescopes and get outside!

The very young crescent moon will rejoin the western evening sky on Monday after sunset, but you’re more likely to see it on the following evening, when it will be positioned less than a palm’s width to the left (southeast) of the planet Mercury. The moon and Mercury will both be visible sitting very low over the northwestern horizon after sunset, surrounded by evening twilight. The best time to see them will occur between 9:15 and 10 p.m. local time when the sky will be darker. Mercury will become a little easier to see every night as it swings wider from the sun.

(Close approach of the Moon and Mercury.)

The moon and Mercury are both being illuminated by the sun. But the moon will show a thin crescent while Mercury, viewed in a telescope, will show a largely full disk. That is because the moon is closer to us than the sun, while Mercury is on the far side of the sun. Events like these, when solar system objects displayed differences in illuminated appearance, allowed early astronomers to reason out the geometry of our solar system.

During early evening on Wednesday, the young crescent moon will sit less than a palm’s width to the upper left (east) of the reddish planet Mars. Look for the pair in the north-northwestern sky among the stars of Gemini before they set at about 11 pm local time. On the same evening, the crescent moon will be sitting very close to a medium-bright, double star named Wasat (also known as Delta Geminorum). That star marks the waist of Gemini’s easterly twin, Pollux.

(Close approach of the Moon and Mars.)

Observers located in the southern and eastern portions of the continental USA can watch the crescent moon occult that close pair of stars at about 9:30 pm EDT. To see the moon’s dark leading edge cover them (they’ll suddenly wink out), be sure to start watching the event before about 9 pm EDT. The sky won’t be dark yet, but binoculars and backyard telescopes will still show Wasat near the moon. Every minute, the moon will creep closer to the star. To find out exactly when the occultation starts and ends where you live (it varies), use a free astronomy app like SkySafari 6 or Star Walk 2, or load Stellarium on your computer.

On Thursday night, the waxing crescent moon will move into Cancer (the Crab). The moon will set a little before midnight local time. Once the sky becomes fully dark, grab your binoculars and head outside. The moon will be situated within a few finger widths to the lower right (west) of the big open star cluster called the Beehive (or Messier 44). The slim moon and the cluster’s loose knot of dozens of stars should all fit within your binoculars’ field of view. Just put the moon in the lower right part of the binoculars’ view and look for lots of stars in the upper left. To help you navigate Asellus Australis, Cancer’s brightest star, will shine about two finger widths to the left of the star cluster. Use that star to find the Beehive even after the moon moves away.

On Saturday night, the nearly half-illuminated moon will land a few finger widths above the bright, white star Regulus, in Leo (the Lion).

Jupiter will shine as a blazing beacon of light in the eastern sky all night after it rises at about 9 pm local time. Due to Jupiter’s rapid 10-hour rotation period, the Great Red Spot (or GRS) is only observable from Earth every 2nd or 3rd night and only during a predictable three-hour window. The GRS will be easiest to see using a medium-sized, or larger, aperture telescope on an evening of good seeing (steady air).

If you’d like to see the Great Red Spot in your telescope, it will be crossing the planet after midnight tonight (Sunday). More GRS viewing opportunities occur in the hours surrounding 10:30 pm EDT on Wednesday evening, after 11 pm EDT on Friday.

(The view of Jupiter from the Solar Walk app.)

Yellowish Saturn will be rising a little before 11:15 pm local time this week. It is sitting in the area just to the left (east) of the stars that form the teapot-shaped constellation of Sagittarius (the Archer). It’s noticeably dimmer than Jupiter and will be located about 2.5 fist diameters to the left (east) of Jupiter all summer. Dust off your telescope because even a small one will show its rings and several of its brighter moons!

Distant and dim, blue Neptune is in the southeastern pre-dawn sky, among the stars of Aquarius (the Water-Bearer). The planet will rise before 2:30 am local time. After mid-June, it will be part of the evening sky. Brighter, blue-green Uranus is rising at about 4:30 am local time, among the stars of Aries (the Ram).

Last to rise is our bright, next-door neighbour Venus. She is sitting low in the east-northeastern pre-dawn sky this week, creeping ever-closer to the rising sun. Venus will shine with a steady, unmoving light — unlike airplanes.

The Big Dipper as a Sky Tool

(Use the Big Dipper to practice how to specify how far apart in the sky objects are.)

At this time of year the Big Dipper asterism, part of the larger constellation of Ursa Major (Big Bear), sits just to the west of the zenith after dusk. When viewed while facing northeast, the dipper’s downward-facing bowl spills into its little counterpart, and its handle points to the right. Continue the arc of the dipper’s handle and “Arc to Arcturus”, the bright orange star in Böotes (the Herdsman). Continue the arc farther to “Spike to Spica”, the brightest star in Virgo (the Maiden). Extending a line from the double star Mizar at the bend of the dipper’s handle, and diagonally through the dipper’s bowl stars, you will “Cast to Castor” in Gemini (the Twins).

You can use the Big Dipper to practice how to specify how far apart in the sky objects are. The depth of the bowl is 5 degrees. For most people, that’s equivalent to three or four finger widths (with your hand at arm’s length). The width across the bowl is 10 degrees, or about a clenched fist’s width. The length of the dipper from the star Alkaid at the handle-tip to Dubhe at the far rim, is 25 degrees. Most people can span this with a surfer’s salute — outstretched thumb-tip to pinky fingertip. Kids’ hands are smaller, so the angles I quoted above will be smaller for them.

And don’t forget that the moon covers only half of a degree — so even a child can cover it with the tip of a pinky finger at arm’s length. Try it this week!

Astronomy Skylights for the week of June 2nd, 2019 by Chris Vaughan.

Keep looking up, and enjoy the sky when you do. I love questions and requests — so, send me some!

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