The Sky: November 6-11: Double clusters and double stars

Special to, November 6, 2023, 2023

Excerpts from weekly Sky&Telescope report.


■ Perseus is high in the northeast these November evenings. The Perseus Double Cluster is below W-shaped Cassiopeia; the W is currently standing on end. Count down the segments of the W starting from the top. The third segment points almost straight down. Follow that direction down by twice its length and there you are.

But Perseus has many other open clusters! One of the nicest is M34 between Algol and Gamma Andromedae. And the Double Cluster itself is closely surrounded by an array of telescopic double stars, obscure clusters, and little asterisms.


■ Around 8 p.m. this week, the Great Square of Pegasus stands in its level position very high when you face south.

■ M33, the low-surface-brightness Pinwheel Galaxy in Triangulum, may be gravitationally bound to the bigger, brighter Andromeda Galaxy 15° away. They’re at about the same distance from us.


■ Look east before and during early dawn Thursday morning the 9th. If the sky is clear, the close pairing of Venus and the waning crescent Moon will grab your eye. These are the two brightest celestial objects after the Sun. Note the earthshine on the Moon’s night portion. A telescope reveals the Moon’s terminator running along the edge of Oceanus Procellarum, and Venus displaying its slightly gibbous phase.

Catch the Moon visiting Venus in early dawn Wednesday morning. They’ll be only about 1° or 2° apart as seen from the Americas.


■ Vega is the brightest star high in the west on November evenings. Its little constellation Lyra extends to its left, pointing as always toward Altair, the brightest star in the southwest.

Three of Lyra’s leading stars, after Vega, are interesting doubles. Barely above Vega is 4th-magnitude Epsilon Lyrae, the Double-Double. Epsilon forms one corner of a roughly equilateral triangle with Vega and Zeta Lyrae. The triangle is less than 2° on a side, hardly the width of your thumb at arm’s length.

Binoculars easily resolve Epsilon. And a 4-inch telescope at 100× or more should resolve each of Epsilon’s wide components into a tight pair.

Zeta is also a double star for binoculars; much tougher, but plainly resolved in a telescope. And Delta Lyrae, upper left of Zeta by a similar distance, is a much wider and easier binocular pair.


■ Action at Jupiter. The Great Red Spot should cross Jupiter’s central meridian around 7:58 p.m. EST. Then Io crosses onto Jupiter’s face from the east at 10:28 p.m. EST, followed by its little black shadow at 10:51 p.m. EST. Satellite and shadow exit from Jupiter’s western limb a little more than two hours later.


■ By about 8 or 9 p.m. Orion is clearing the eastern horizon (depending on how far east or west you live in your time zone). High above Orion shines orange Aldebaran. Above Aldebaran is the little Pleiades cluster, the size of your fingertip at arm’s length.

Down below Orion, Sirius rises around 10 or 11 p.m. No matter where in the sky they are, Sirius always follows two hours behind Orion. Or equivalently, one month behind Orion.


■ Vega remains the brightest star in the west in early evening. Its little constellation Lyra extends to its left. Somewhat farther left, about a fist and a half at arm’s length from Vega, is 3rd-magnitude Albireo, the beak of Cygnus. This is one of the finest and most colorful double stars for small telescopes.

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