Scheduled time for Public Observing: 9pm – 11pm

Solar System Objects:

The Moon: will be past full phase tonight (92% illuminated) and rise late, at 10:15pm. By 11:00 it will reach only 6° altitude, not high enough for useful telescopic observation.


Venus will be low in the Western sky, 19° high at 9pm, just below the limit for the 20″ refractor. It should still be visible early if any telescopes are set up outside the observatory. Being closer to the sun than we are it shows phases like the moon, tonight it will be 70% illuminated.

Jupiter will be well-placed in the South, the positions of it’s brighter satellites is shown below. The Great Red Spot will transit (cross the center) of Jupiter at 8:18pm tonight, so should also be visible early. Since Jupiter rotates once in only 10 hours, it takes only 2-1/2 hours for the GRS to go from the center to the edge.

Image courtesy of Starry Night (R) Orion Special Edition, Version: 6.2.3 kcEW, Imaginova (R) Corp.

Saturn will be rising in the SE, 21° high by 11pm, just above the limit for the 20″ telescope. If we’re lucky we might get a look, and it will be visible in any telescopes set up outside. The image below was taken with one of those ‘scopes.

Mars will rise at 10:30pm and will not be very high in the East by 11:00, near the moon. It does, however, appear larger than it has in years (currently 20.7 arc seconds across), heading for a maximum of 24.3″ on July 31. The ongoing planet-wide dust storm is showing some recent signs of clearing.

Double Stars:

One example of an interesting binary star is 61 Cygni. At a distance of 11.4 light years, it’s the fourth closest star system to the sun that’s visible to the naked eye (barely). It consists of two evenly matched orange-yellow dwarf stars that are easily separated in the eyepiece, in a beautiful background of fainter stars. It’s proper motion (motion against the background) is visible in only a couple of years – see the video here.

Deep-Sky Objects:

The globular star cluster M5 will be above Jupiter, and would show well in the 20″. M5 is 24,500 light years away, 160 l.y. in diameter, and contains over 100,000 stars.

Image by ASGH member Joe Roberts, see his website here.

Several other globular clusters will be observable, along with a few planetary nebulae (using a light-pollution filter) such as the Ring Nebula (M57) and the Blinking Planetary (NGC 6826).

Man-made Objects:

International Space Station (ISS): The ISS will not be visible tonight, it is currently making early morning passes above this area.

Iridium Satellites: These satellites can produce bright flares from their antenna arrays. *Update* at 9:56pm Iridium 64 is predicted to flare to a magnitude of -5.9 (brighter than Venus), at an elevation of 47° in the constellation Cygnus, in the East.