The Moon & Pleiades

If you're up late, say 11pm or midnight, look for the moon low in the east. Immediately to its upper right is a cluster of stars known as the Pleiades. If the glare of the moon interferes with your view of this bright cluster, use your hand to block off the moon.

The Pleiades, also known as the Seven Sisters, is one of the few clusters visible to the naked eye under city skies. At least 6 stars are visible even without binoculars.

Constellation Lyra

Vega, the brightest star in the Summer Triangle, belongs to the constellation Lyra. It's the brightest star in the constellation. At magnitude 0, it's also the fifth brightest star in the sky.

Hanging off Vega are two pairs of stars. Two of them, the brighter of the pairs, are named Sheliak and Sulafet. The four stars form a parallelogram, as shown in the chart above.

Note another star labeled the Double Double. If your eyes are sharp enough, this star appears as a double star. These stars are doubles themselves, making the Double Double a quadruple star system. A sharp telescope on a good night will show all four stars.

References:

The 10 Brightest Stars
Constellation Lyra

Constellation Cygnus

The stars of the Northern Cross belong to the constellation Cygnus, the swan. Deneb, at magnitude 1.25, is the brightest of the stars. It's also among the top 20 brightest stars in the sky.

Deneb marks the tail of the swan. In fact, Deneb is Arabic for "tail." At the opposite end is the star Albireo marking the head of the swan. Albireo is a popular among amateur astronomers because it appears as a beautiful yellow and blue double star through a telescope.

References:

List of Brightest Stars
Constellation Cygnus
Albireo

The Northern Cross

Take a closer look at Deneb, the northernmost and faintest star in the Summer Triangle. Off to the south, or the right, of Deneb are three stars. The middle star is labeled Sadr in the chart above. Farther to the south, or right, is the fainter star Albireo.

These stars make up what is known as the Northern Cross. Deneb marks the top of the cross. Sadr is at the intersection of the arms of the cross, and Albireo is at the bottom of the cross.

Deneb to Albireo spans 22°. If you hold your outstretched hand at arm's length against the sky, the width from your thumb to your little finger covers about 25°. The Northern Cross should fit within your outstretched hand.

References:

Constellation Cygnus
Star Science in the Autumn Sky

The Summer Triangle

Go outside about half an hour after sunset. One by one, the brightest stars in the sky will start popping out. If you look directly overhead, the first three stars to appear form the asterism known as the Summer Triangle. Even though it's almost autumn, the Summer Triangle is still high overhead at nightfall.

Vega, the star farthest to the west, is the brightest among the three. Altair, towards the south, is the second brightest. Deneb, the one farthest north, is the faintest.

Unlike other asterisms that usually belong to a single constellation, the three stars of the Summer Triangle belong to three different constellations. Vega is the brightest star in the constellation Lyra. Altair is in the constellation Aquila. And Deneb belongs to the constellation Cygnus.

References:

Skywatchers Guide: Summer Triangle helps orientation, observation

Moon & Neptune

The moon will be less than 1° from Neptune tonight. One degree is the width of your little finger held at arm's length.

Neptune, at magnitude 7.8, is too faint to see naked-eye. But if you own a telescope, it will be easy to find using the moon as your guidepost.

You can also try finding Neptune with binoculars. The typical binocular has a 5° field of view, so Neptune and the moon, with only 1° separating the two, should both fit in the field of view . You may want to move most of the moon out of the field of view though. Otherwise its glare may keep you from seeing the surrounding stars and planet.

Use the chart below to find Neptune.

Astronomy Tonight: Venus & Mars

If you have a clear view of the western horizon, you'll see Venus & Mars practically on top of each other. Look very low to the west 30 minutes after sunset. Venus will be only 1/3° north (upper right) of Mars. One-third degree is less than half the width of your little finger held at arm's length.

Astronomy Tonight: The Moon to the Left of the Teapot

Again, look to the south for the moon. If you've learned how to recognize the teapot asterism in Sagittarius, you'll see that the moon is just to the left of the teapot's handle. The bright "star" to the upper right of the moon is the planet Jupiter.

Tuesday, September 9

Astronomy Tonight: The Moon in Sagittarius

The moon has now moved into Sagittarius. If you've learned how to recognize the teapot asterism in Sagittarius, you'll see that the moon is just above the teapot's spout. Note bright Jupiter to the upper left.

Monday, September 8

Astronomy Tonight: The Moon Between Sagittarius and Scorpius

Look to the south for the moon. It has now moved between the constellations Sagittarius and Scorpius.

This is a perfect time to learn how to recognize the two constellations. Sagittarius to the left of the moon looks like a teapot, and Scorpius to the right looks like a giant letter J. Also note bright Jupiter to the left of Sagittarius.

Sunday, September 7

Astronomy Tonight: The Moon and Antares

Look for the moon to the south. The bright star Antares will be just to the upper left of the moon. The two will be about 1° apart. One degree is approximately the width of your little finger held at arm's length.

Antares is the brightest star in the constellation Scorpius. If you haven't learned how to recognize Scorpius, now is a good time with the moon to guide you.

Saturday, September 6

Astronomy Tonight: Mercury, Venus and Mars Triangle

Thursday, September 4


Mercury, Venus and Mars will form a small triangle tonight. You'll need a very low western horizon to see this. Look 30 minutes after sunset but not much later. If it's not dark enough, use binoculars.

Astronomy Tonight: Mercury, Venus, Mars and Moon

Tonight the moon will join Mercury, Venus and Mars. Again, you'll need a very low horizon. If you live along the west coast, this is a perfect time to head for the beach.

About half an hour after sunset, look just above the western horizon for the moon. Mercury, Venus and Mars will be just to its upper right. You'll need binoculars to see all three planets if it's not dark enough. And don't wait too late or the planets and the moon will sink below the horizon.

Monday, September 1