Scheduled time for Public Observing: 8pm – 10pm

The 20″ refractor is down for repairs.  We will be using the 16″ Meade in the small dome on the left side of the Observatory.  There is a narrow, spiral metal staircase that leads to the telescope, and the dome is also much smaller than the main dome so we can only take small groups at a time. 

Solar System Objects:

The Moon: will be nearly full, 90% illuminated, but surface details will still be well-defined along the terminator on the left side of the image below.

Crater of the month: Aristarchus is a young crater (only 450 million years old), and appears bright with a prominent ray system. It’s 24 miles in diameter and over 2 miles deep, look for terracing on the interior carter wall and for Schroter’s Valley, to the left of the crater in the image below. It was a river-like flow of lava at one time. Please see the article here for more information and excellent pictures from the Lunar Reconnaissance Orbiter.

Image copyright (c) Virtual Moon Atlas / ,with thanks to Christian Legrand & Patrick Chevalley.


Mars will be observable with a telescope until 9pm, after which it will be too low in the sky, and nearby Uranus will reach the limit at 8:45. While appearing close together in the sky, Mars is 154 million miles away and Uranus is 1890 million.

Deep-Sky Objects:

Double Stars: Castor is a bright binary star in Gemini. It will be high overhead tonight, 73 degrees in altitude at 8pm. Castor can be seen as a double star in almost any telescope, and the orbital motion of its components is visible within a human lifetime. Some years ago it was difficult to “split” as a double, now it’s easier because their separation has increased. This article from Sky and Telescope magazine gives information on other interesting stars in the area.

Nebula and Star Clusters: There are a few open clusters of stars and one nebula that wouldn’t normally be too difficult to see, but they all will appear fairly close to the moon tonight, reducing their visibility. The open clusters are M35 in Gemini and M36, M37, and M38 in Auriga, and the nebula is M42 the Orion Nebula. Even if there isn’t much nebulosity visible, the Trapezium at the center of M42 can be seen as a quadruple star system.

The open star cluster M37 is shown below as captured with an 8″ telescope and video camera.

Star Charts and other Information:

A very useful monthly star chart can be downloaded here from, giving information on objects visible with the unaided eye, binoculars, or telescope.

For current astronomical events see Sky and Telescope Magazine’s “This Week’s Sky at a Glance”.