I don't know how to decide what to view on any given night, but when I get the amateur astronomy itch I sit down for a brief session with my favorite planetarium program Xephem. For me it has the right combination of utility, speed, and computer requirement.

These images show just some of the displays you can get from Xephem to help you plan your evening. Whether you want to know what stars are out, what Jupiter's moons are doing, or the phase of the Moon, these displays will tell you. You're welcome to use this web page as a quick evening reference, but you can plan even better if you just get Xephem. If you get xephem on you own computer, you can adjust the view for anywhere in the world, and step through time to see exactly when specific events will occur.

These displays are good for the evening of 09/03/2010. I've chosen Denver, Colorado as the viewing site, and the view at 8:00 PM Denver time. It seemed that it was a good median point of view, as Denver is centrally located in the U.S.

This xephem Data Table display shows some handy information to help you plan your moon and planet observing sessions.

The table shows data for the Moon, Venus, Mars, Jupiter, and Saturn. The data listed shows each object's visual magnitude (VMag), Angular size in arc-seconds (Size), and 24 hour clock riset time (RisTm) and set time (SetTm) referenced to Denver Local Time.

This xephem Solar System view shows where the inner planets are in their orbits with respect to one another. I reduced the scope of the diagram to only cover the inner planets since for observing considerations, their positions more more significant.

In this view the planets orbit in a counter-clockwise direction. A glance at this display will help you determine if the planets are going to be morning or evening objects (also see previous image), what the phases of Mecury and Venus will be, and whether or not Mars is near opposition.

This is a very truncated version of the xephem Moon view. With the Xephem program you can set the size of the image, turn on labels of the Apollo landing sites, and select from a large list of lunar features which will then be labeled on the image.

This is the way the moon would appear to the naked eye.

This xephem Mars view shows the appearance of Mars at the chosen time. Though not visible in this reduced size image, the Xephem live display also shows the angular size of Mars, which varies considerably depending upon the relative positions of Earth and Mars.

The images is a graphical representation of Mars with about a 0.5 arc-second limited view. Keep your eyes on it, as about every two years Mars and Earth come fairly close together, and the details become more clear.

For another indicator of what side of Mars is visible, check out the Sky and Telescope Mars Viewer.

I use this xephem Jupiter view feature of Xephem quite a bit. It shows the position of Jupiter's satellites at any given time, and will also show the Red Spot when in view.

I enjoy looking for the sometimes elusive Great Red Spot, and like especially to watch the moon shadows as they move across the face of Jupiter.

The moon labels are I=Io, II=Europa, III=Ganymede, and IV=Callisto.

This is a typical view through a telescope with a star diagonal. The planet rotates from right to left.

To find out when the Great Red Spot will transit, check out the Sky and Telescope GSR Applet.

This xephem Saturn view display is also handy. It will show the inclination of Saturn's rings at the time chosen, and display the position of the moons of Saturn.

You can select the magnitude limit for the moons you wish displayed, and the field of view to consider. The display here shows a pretty large field of view to show the moon positions.

This is a typical view through a telescope with a star diagonal. The planet rotates from right to left.

This display shows only moons as bright as magnitude 13. The table below shows the moons labels and typical magnitudes. Depending upon your seeing conditions and telescope size, you may not be able to see them all.