In the Sky This Month

Epsilon Eridani is the third-closest star system that’s visible to the unaided eye, at a distance of just 10.5 light-years. It is well up in the south-southeast at nightfall, far to the right of the top right corner of Orion.

Under dark skies, the Milky Way is in good view tonight. In early evening, it extends along the body of Cygnus, the swan, in the west-northwest; through M-shaped Cassiopeia, higher in the sky; then between Orion and the twins of Gemini, in the east-southeast.

A star cluster discovered by Caroline Herschel, one of the first women astronomers, is in view tonight in Canis Major, the big dog. It stands to the lower left of Sirius, the brightest star in the night sky, and is visible through binoculars.

The Orion Nebula is in the southeast at nightfall, to the lower right of Orion’s Belt. It looks like a big, faint star. Instead of a single star, though, it’s a giant complex of gas and dust that has given birth to thousands of stars.

The Moon is low in the sky at dawn tomorrow. The bright star Antares, the heart of the scorpion, is close by. Although the Moon is a thin crescent, the dark portion of the lunar disk is illuminated by earthshine, which is sunlight reflected from Earth.

Mighty Orion the hunter has a mighty resting spot for his tired feet: Cursa, the second-brightest star of Eridanus, the river. As night falls, the star stands above Orion’s foot, Rigel, the hunter’s brightest star.

If you long for warm nights of skywatching, look at the summer sky about an hour before sunrise. The stars of summer evenings appear just before dawn in winter. So tomorrow morning, you can see the stars as they will look during July evenings.

Jupiter is at its brightest for the entire year today, shining brighter than any other planet or star in the night sky. The twins of Gemini are close by. Pollux, the brighter twin, is close to the left of Jupiter at nightfall. Castor is farther to the upper left.

Three cats pad across the sky late tonight. The brightest is Leo, the lion, marked by its brightest star, Regulus. Leo Minor, the little lion, stands to Leo’s north. The third cat, Lynx, stretches overhead, but you may need the eyes of a lynx to spot it.

The planet Jupiter is especially vibrant now. It reaches opposition this weekend, when it lines up opposite the Sun in our sky. It rises around sunset and is in view all night. The planet is also closest to us, so it shines at its brightest.