An open-source planetarium that shows a realistic sky in 3D, just like what you see with the naked eye.
(the "Pro" version) is actively updated. Upgrading supports the solo developer and grants access to: VR Support: Full compatibility with Valve Index, Vive, and Oculus. Improved Graphics: how to download space engine free
If you are a casual observer, the free version is sufficient. However, if you are looking to spend hours exploring the universe in high fidelity, the $29.99 cost on Steam is well worth the investment. An open-source planetarium that shows a realistic sky