This Week’s Sky at a Glance, June 12 – 20

Some daily sky sights among the ever-changing Moon, planets, and stars.

The slow nova in Sagittarius has faded to magnitude 8.5 as of June 17th. See article with charts and a link to an up-to-date light curve.


Friday, June 12

The two brightest stars high on June evenings are Vega, the brightest high in the east, and Arcturus, way overhead toward the southwest. They're relatively close to us: 25 and 37 light-years, respectively. Vega is more than twice as hot as Arcturus; their absolute temperatures are 9,600 and 4,300 kelvins, respectively. Which is why Vega shines pale bluish white, while Arcturus appears pale yellow-orange.

They're getting closer. . . .

Watch the two brightest planets drawing closer together every day for the rest of June.

Saturday, June 13

Jupiter and bright Venus have closed to within 11° of each other in the west at nightfall. Once the sky is dark enough, binoculars can show that this evening, Venus shines in the top fringe of M44, the Beehive Star Cluster.

Sunday, June 14

Saturn is the brightest point glowing in the southeast to south these evenings. The stars of upper Scorpius glitter below it.

For instance, to the the lower left of Saturn by 3½° (about two finger-widths at arm's length) is Beta Scorpii, a fine double star for telescopes. Just 1° below Beta is the very wide naked-eye pair Omega1 and Omega2 Scorpii, not quite vertical. Binoculars may show their slight color difference.

And to Beta's left by 1.6° is Nu Scorpii, another fine telescopic double. And, high power in good seeing reveals that Nu's brighter component is itself a close binary, separation 2 arcseconds.

Monday, June 15

Spica shines in the southwest after dark — very far to the right of Saturn, Antares and company. Look below Spica (by about two fists at arm's length) and a bit right for the four-star constellation Corvus, the Crow — a spring sign on its way down and out as spring nears its end.

Tuesday, June 16

Look very high in the northeast for the Big Dipper hanging down by its handle. The middle star of the handle is Mizar, with tiny little Alcor right next to it. On which side of Mizar should you look for Alcor? As always, on the side toward Vega! Which now dominates the eastern sky.

Wednesday, June 17

Can you see the big Coma Berenices star cluster? Does your light pollution really hide it, or do you just not know exactly where to look? It's currently in the west after dark; look 40% of the way from Denebola (Leo's tail) to the end of the Big Dipper's handle (Ursa Major's tail). Its brightest members form an inverted Y. The cluster is about 5° wide — a big, dim glow when seen in at least a moderately dark sky. It nearly fills a binocular view with its sparsely scattered points.

Thursday, June 18

With summer just three days away, the Summer Triangle now stands high and proud in the east after dark. Its top star is bright Vega. Deneb is the brightest star to Vega's lower left (by 2 or 3 fists at arm's length). Look for Altair a greater distance to Vega's lower right.

Venus and Jupiter are approaching conjunction.

Don't miss the twilight sky show now going on in the west.

Friday, June 19

The Venus-Jupiter pairing is growing ever more striking in the west at dusk, as they near their June 30th closest approach. And as twilight fades this evening, look below them for the waxing crescent Moon as shown here.

Saturday, June 20

The Moon, Jupiter, and Venus form a striking triangle in the west during and after dusk, as shown here. Regulus and the Sickle of Leo look on from the upper left. Think photo opportunity! The whole array is less than 20° tall or wide.

Tomorrow, the 21st, is the longest day of the year in the Northern Hemisphere; the shortest in the Southern Hemisphere. The solstice is at 12:38 p.m. on the 21st EDT (16:38 UT), marking the start of northern summer. Because the time of the solstice so closely splits the nights before and after in the Eastern time zone, you might end up going to two Midsummer Night parties!

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Want to become a better astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.

This is an outdoor nature hobby. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential guide to astronomy.

Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The standards are the little Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger and deeper Sky Atlas 2000.0 (stars to magnitude 8.5); and once you know your way around, the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.

You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, the bigger Night Sky Observer's Guide by Kepple and Sanner, or the beloved if dated Burnham's Celestial Handbook.

Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically (meaning heavy and expensive). As Terence Dickinson and Alan Dyer say in their Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."


This Week's Planet Roundup

Illustration of Jupiter's Great Red Spot shrinking from 1890 to 2015, by Damian Peach.

Jupiter fans are well aware that the Great Red Spot has been shrinking for the last century and that the process may be speeding up. In this striking illustration, Damian Peach took his April 13, 2015 image (right) and morphed the Red Spot to match its size in photographs from around 1890 (left). North is up. He writes, "Some fairly decent black-and-white photos taken at Lick Observatory in 1890-91 show the GRS well, and allow measurement of the storm (which we already know was around 36,000 km in length at this time from multiple observations and photos.) Since there are no colour or high-resolution photographs from those times, this presents a neat comparison of how it would look to us today if were still as large, and just how much of its grandeur has been lost." Click here for full-size image.

Mercury is deep in the glow of sunrise.

Venus (magnitude –4.5) is the brightest point in the west during and after twilight. Jupiter, to Venus's upper left, is the second-brightest. They're closing in on each other day by day: from 12° apart on June 12th to 7° on the 19th.

Venus and Jupiter will have a spectacularly close appulse (closest approach) on June 30th, when they'll appear just 1/3° apart at dusk in the time zones of the Americas. (Their conjunction in right ascension is on July 1st, when they're slightly farther apart.)

Mars is hidden behind the glare of the Sun.

Saturn (magnitude +0.2, above the head of Scorpius) is highest in the south after dusk. Some 12° lower left of Saturn is twinklier orange Antares, less bright. In a telescope, Saturn's rings are tilted a generous 24° from edgewise.

Uranus (magnitude +5.9, in Pisces) is low in the east before dawn begins to brighten.

Neptune (magnitude +7.9, in Aquarius) is in the southeast before the first light of dawn.

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All descriptions that relate to your horizon — including the words up, down, right, and left — are written for the world's mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America.

Eastern Daylight Time (EDT) is Universal Time (UT, UTC, or GMT) minus 4 hours.

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“This adventure is made possible by generations of searchers strictly adhering to a simple set of rules. Test ideas by experiments and observations. Build on those ideas that pass the test. Reject the ones that fail. Follow the evidence wherever it leads, and question everything. Accept these terms, and the cosmos is yours.”

— Neil deGrasse Tyson, 2014

 


2 thoughts on “This Week’s Sky at a Glance, June 12 – 20

  1. mary bethmary beth

    Agreed! Celebrate the Solstice all weekend – I think I will even start Friday night with the beautiful crescent moon!

  2. Anthony BarreiroAnthony Barreiro

    I’ve been enjoying watching Venus from the sidewalk in front of my home, starting when the Sun drops below the rooftops across the street, about 45 minute before official sunset. Venus is easily visible in binoculars, and then once you know where to look she shows up to the naked eye as a bright white point of light against the blue sky. Through a small refractor at 38x magnification, Venus is obviously slightly crescent (or decrescent, if you’re an etymological stickler). People who have never seen Venus through a telescope consistently say she looks like “a half Moon!” This can lead to an interesting discussion of the orbits of Venus and Earth around the Sun, Galileo’s observation of the phases of Venus, and how she would look in a geocentric vs. a heliocentric solar system.

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