Stellarium - Photo Realistic Sky Generator - Archlinux

Stellarium is a free open source planetarium for your computer. It shows a realistic sky in 3D, just like what you see with the naked eye, binoculars or a telescope. It is being used in planetarium projectors. Just set your coordinates and go.

Features:

Sky:

default catalogue of over 600,000 stars, constellations for 20+ different cultures, images of nebulae (full Messier catalogue),extra catalogues with more than 210 million stars, asterisms and illustrations of the constellations,  realistic Milky Way, very realistic atmosphere, sunrise and sunset, the planets and their satellites

interface:

a powerful zoom, time control, multilingual interface, spheric mirror projection for your own low-cost dome, all new graphical interface and extensive keyboard control, fisheye projection for planetarium domes,  telescope control

visualisation:

equatorial and azimuthal grids,  eclipse simulation, supernovae simulation, star twinkling, shooting stars, skinnable landscapes, now with spheric panorama projection

customizability:

plugin system adding artifical satellites,  ability to add new solar system objects from online resources..., ocular simulation, telescope configuration and more, add your own deep sky objects, landscapes, constellation images, scripts...

Official Sites:

http://www.stellarium.org/

Installation in Archlinux:

$sudo pacman -S stellarium

Here's some screenshot of Stellarium:

To use stellarium for viewing sky landscape is easy, just scroll in/out your mouse and see the object that you want to see.

You can also change your location to see sky in another place:

Another view of lens that you can try:

Stellarium is good apps to learning sky and object such as planet, stars, moon, etc. And it's free.
Enjoy.
^_^