Summer’s signature star pattern, the Summer Triangle, stands well up in the east on July evenings. Its brightest member is Vega, at the top of the triangle, with Deneb to the lower left and Altair to the lower right. At the same time, the curving body of Scorpius and the Teapot of Sagittarius scuttle low across the south, anchoring the summer Milky Way.
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In the Sky This Month
July 31: Last-Quarter Moon
For the second time this month, the Moon is at last quarter. It lines up at a right angle to the line between Earth and the Sun. In that position, the Sun lights up half of the Moon’s Earth-facing hemisphere, so the Moon looks like it’s been chopped in half.
August 1: Saturn at Opposition
Saturn is at its best for the year. The planet rises around sunset, is in view all night, and shines at its brightest, like a bright golden star. It’s low in the southeast as night falls and in the southwest at first light. The brighter planet Jupiter follows it.
August 2: 61 Cygni
After the Sun, the first star whose distance was accurately measured was 61 Cygni. It is part of Cygnus, the swan, which passes high overhead tonight. 61 Cygni is about 11 light-years away. It appears fairly close to Deneb, the swan’s tail.
August 3: Astonishing Mira
Mira, a star that changes brightness, should be at its best this month. The star puffs in and out like a beating heart, changing brightness with each beat. It is in Cetus, the sea monster. It is in good view by 2 a.m. and stands halfway up the sky at dawn.
August 4: Saturn at Opposition II
Bright golden Saturn is at its best for the year this week. It is low in the southeast at nightfall and remains in view all night, to the right of brighter Jupiter. Through a telescope, its brightest moon, Titan, looks like a tiny star close to the planet.
August 5: Evening Highlights
Vega stands high overhead this evening, with yellow-orange Arcturus high in the west and pure orange Antares low in the southwest. And under a dark sky, away from city lights, the Milky Way arcs high across the east.
August 6: Delta Cephei
Delta Cephei is one of the leading lights of Cepheus, the king, which is in the north and northeast at nightfall. The star is unstable, so it pulses in and out like a beating heart. It has a small, close companion star.
Last July 1, 4:11 pm
New July 9, 8:17 pm
First July 17, 5:11 am
Full July 23, 9:37 pm
Last July 31, 8:16 am
Times are U.S. Central Time.
Apogee July 5
Perigee July 21
The full Moon of July is known as the Hay Moon or Thunder Moon.