How to plan an observing session with Stellarium

Stellarium is a free, open source planetarium application which allows the night sky to be viewed from any location on Earth, on any date. The software can be downloaded from, together with installation instructions.

Using Stellarium

When you open Stellarium, it adopts the date and time from your computer clock - the first screen looks similar to the image here.

The menu options can be found by hovering your mouse over either the left hand side or lower part of the Stellarium screen. 

Setting your location

To set the location of the telescope you will be using, go to the 'Location window' in the left hand menu, and enter the coordinates and altitude of the telescope in the latitude and longitude boxes: 





Time Zone


20° 42′ 27″N

156° 15′ 21.6″W




30° 40′ 12″N

104° 1′ 12″W



Cerro Tololo

30° 10′ 2.64″S

70° 48′ 17.28″W




32° 22′ 48″S

20° 48′ 36″E



Siding Spring

31° 16′ 23.88″S

149° 4′ 15.6″E



Your view will now change to show the sky at the location you've provided.

Setting the date and time of your observing session

To set the date and time of your observing session, go to the 'Date/Time' window in the left hand menu and change the time and date in the pop-up box to correspond to the date and time of your session. 

Finding objects

Zoom in or out of the sky view in Stellarium by either using the roller ball of your mouse, or using the 'Page Up' and 'Page Down' buttons on your keyboard. 

Set the azimuthal viewing grid on the sky view by clicking on the 'Azimuthal Grid' button in the lower menu. This now shows circles on the sky of different altitudes above the horizon. If you have an altitude limit, for example for viewing object at a minimum 30 degrees above the horizon, then choose objects within the 30 degree circle on this grid.

Mark objects in the sky by clicking on the nebula button in the lower menu. To increase or decrease the number of objects shown in Stellarium, go to the 'Sky and viewing options window' in the left hand menu and use the 'Labels and Markers' sliders to customize your screen. 

Find a list of objects which are above your altitude limit in the sky at the date and time of your session, and using the sky view in Stellarium, choose the best order in which to observe your objects. For each object you should also check its size, and whether it will fit into the field of view of the telescope you are using (to find the field of view of the telescope, go to and click on the relevant telescope). Information on the size of the object selected in Stellarium can be found by a simple internet search on each of your objects, or alternatively, by searching the interactive NGC and Messier catalog online at: