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The Night Sky of June

Dr. Wayne Wooten
Professor of Astronomy

For June 2015, the Moon will be full, the Honey Moon, on June 2nd, so the first two weeks find the moon waning in the morning sky. On June 1st, the almost full waxing gibbous moon passes about 2 degrees north of Saturn in the SE twilight sky. The last quarter moon is high up in the south at dawn on June 15th. The new moon is on June 16th. The waxing crescent moon makes a striking grouping with brighter Venus and fainter Jupiter in the SW twilight on June 19th (Moon just below Venus) and 20th (moon to lower left of Jupiter). The beginning of summer occurs at 11:38 AM CDT on June 21, the longest day of the year, with about 14 hours of daylight.

The moon is first quarter, high up at sunset, on June 24th. The waxing gibbous moon passes 1.9 degrees north of Saturn on the evening on June 29th; this marks the sidereal month, for the take 27.3 days to orbit the earth and return to the same point in the sky, in this case passing slow moving Saturn again.

As June starts, you will note that Jupiter lies about 20 degrees to the upper left of brilliant Venus in the SW twilight. Venus orbits the Sun in 225 days, while it takes Jupiter 12 years for the trip, so in June, Venus catches up quacking to the second brightest planet. Venus is then 53% sunlit, and about 22" of arc across. By monthís end, she has passed greatest eastern elongation (50% sunlit, and 47 degrees east of sun at maximum separation) on June 6th, and then overtakes Jupiter in June 30th. Venus will be a crescent, 34% sunlit, and passing only.3 degrees (less than the moonís .5 degree diameter!) south of Jupiter in one of the most spectacular planetary groupings you can image.

Mercury and Mars both lie too close to the Sun for easy naked eye viewing this month. But in the SE, Saturn, just west of the claws of Scorpius, is a great show all night. Saturnís rings are now open about 22 degrees; they will continue opening up wider until 2017, when they are tilted 27 degrees toward us and the Sun. You may also see some belts and zones on the planetís disk. The largest, Titan, will be seen in any small telescope, but others will need larger scopes to spot.

The winter constellations are being swallowed up in the Sunís glare, but you might spot Sirius low in the SW as June begins. Sirius vanishes into the Sunís glare by mid-June, and this sets the period as "Dog Days", when Sirius lies lost in the Sunís glare. In reality, Sirius is about 20x more luminous than our star, but also lies eight light years distant, while our star is eight light minutes away from us.

The brightest star in the NW is Capella, distinctively yellow in color. It is a giant star, almost exactly the same temperature as our Sun, but about 100X more luminous. Just south of it are the stellar twins, the Gemini, with Castor closer to Capella, and Pollux closer to the Little Dog Star, Procyon. By the end of June, all the winter stars, like Sirius, are vanished behind the Sun.

Overhead, the Big Dipper rides high. Good scouts know to take its leading pointers north to Polaris, the famed Pole Star. For us, it sits 30 degrees (our latitude) high in the north, while the rotating earth beneath makes all the other celestial bodies spin around it from east to west.

If you drop south from the bowl of the Big Dipper, Leo the Lion rides high. Note the Egyptian Sphinx is based on the shape of this Lion in the sky. Taking the arc in the Dipperís handle, we "arc" SE to bright orange Arcturus, the brightest star of Spring.

Spike south to Spica, the hot blue star in Virgo (with Mars now to its lower left), then curve to Corvus the Crow, a four-sided grouping. It is above Corvus, in the arms of Virgo, where our large scopes will show members of the Virgo Supercluster, a swarm of over a thousand galaxies about 50 million light years away from us.

The brightest star of the northern hemisphere, Vega rises in the NE as twilight deepens. Twice as hot as our Sun, it appears blue-white, like most bright stars. Its constellation, tiny Lyra, looks like a parallogram just south of Vega, but was the harp of Orpheus in Greek legends. The Ring Nebula, a dying solar type star, has shed a funeral wreath around itself in this fine photo by EAAA member John VeDepo. It lies at the south end of Lyra, and is visible in binoculars as a tiny smoke ring.

In the southeast, Antares rises about the same time as Vega does, in the brightest of all constellations, Scorpius. Antares appears reddish (its Greek name means rival of Ares or Mars to the Latins) because it is half as hot as our yellow Sun; it is bright because it is a bloated red supergiant, big enough to swallow up our solar system all the way out to Saturnís orbit! Saturn lies to west of the claws of Scorpius this month, and is about as bright as Antares, but more yellow in color.

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