Viewers

AladinAladin could be thought of as an astronomy browser. Instead of the internet, Aladin browses through astronomy images, density maps, and other astronomy sources, e.g. Hubble images, the Simbad database, and the VizieR service. You select the item you wish to view and it automatically downloads a view of the item selected.

This program provides access to professional quality telescope images in several wavelengths.  In effect you are looking through a very large telescope. The images are downloaded from the internet so some displays take a few seconds to update—your results would depend of course on the connection speed and on how many databases are being utilized. One can apparently download files for offline viewing.

I could superimpose various views in to one and I could open up to 16 panels with images in each.

It was one of only two programs which indexed every star and deep space object in my test sample as well as showing several images of each item. You can also point at a specific location using the right ascension and declination coordinates.  You can bookmark views.

Since Aladin is a sky atlas image viewer and not a planetarium program it has no solar system objects in its index. Obviously there could be images of the solar objects in many of these images but it's beyond my ability to locate them.

Requires Java 1.5 and runs under Windows, Linux, and Mac.

Sky-Map.orgSky-Map.org (aka WikiSky) is an online viewer utilizing your browser. The images here are in color and come from several sources, e.g. DSS2 all Sky Survey, IRAS Infrared Sky Survey, and user uploaded photos.

The index also found every star and deep space object in my test sample.  Oddly it also indexed the location of the planets but no images were available.

The website allows one to upload an image for display in the catalog.  Some of the views have many layers of images each opaque to the ones beneath.  Left clicking on an area with one or more images opens a popup window where you can select the desired image for viewing.  When zoomed out a bit the layered images look a bit odd.

Requires an Internet connection and browser.

Planetariums

Cartes du CielCartes du Ciel (aka Skychart) is a very easy to use planetarium program.  Its in depth index found every object in my test sample with the exception of UGC 9128.  Additional catalogs for stars down to magnitude 16 (UCAC3) are available on the website, along with several specialty catalogs.  There are instructions for adding the entire PPMXL catalog (magnitude 20), which I didn't attempt as it required 148 GB of hard disk and 24 GB of ram.

Cartes du Ciel has a calendar calculating ephemerides for twilight, planets, sun, moon, comets, asteroids, and solar and lunar eclipses between any two dates.  And there is a variable star observer with the predictions of minima and maxima for many variable stars for the next couple of cycles.

Cartes du Ciel can control a computerized telescope mount.

The program includes images of many deep space objects right in the planetarium window.  I didn't notice any actual stellar images or planetary images.  However, the online documentation indicates that planetary images are available in the Linux version.  No bookmarks. 

Windows, Linux, and Mac versions.

Computer Aided AstronomyComputer Aided Astronomy (aka C2A) was also fairly easy to use.  Its index is second only to Cartes du Ciel in thoroughness.  There are several additional catalogs for download.

There are a lot of images included with the program.  Unlike several of the other planetarium programs the images are viewed through a separate window in the image browser.  If there is an internet connection, the program can download images from either the ESO or the STScl sky surveys for display in either the image viewer or directly in the planetarium field of view.

I liked the data section to the left of the planetarium window with the details about the object on display.  I liked the ability to move forward or back through recent views and the ability to bookmark views.

Computer Aided Astronomy has an ephemeris generator which can generate tables for the sun, planets, moon, comets, and asteroids between any two dates. There are tools to generate trajectories of planets, asteroids, and comets between any two dates.  One tool shows the moon phases for the entire month.  The Ecliptic View tool displays an animated view of the solar system with comets and asteroids.

Computer Aided Astronomy can control a computerized telescope mount.

Windows only.

StellariumStellarium creates fairly realistic views of the sky. The basic program has over 600,000 stars (roughly up to magnitude 9.9) with another 240 million available as add-ons.  This is the only free program that shows constellation groupings for other cultures. 

The zoom in shows actual images of planets and some deep space objects.

Stellarium provides many visual effects, including the Milky Way, twinkling stars, shooting stars, clouds, and light pollution. Several landscapes are included.

The telescope control plug in allows Stellarium to control a computerized telescope. The Satellites plug in calculates and renders satellites in Earth orbit from NORAD/TLE data.

Its catalog is weak in comets and asteroids.

Windows, Linux, and Mac versions.

Additional information