Astro landscapes are night time landscapes with an interesting sky above, such as the Milky Way, a beautiful Aurora, unique light phenomena or just a starry sky. However, it also needs to have an interesting landscape or foreground for a balanced composition. The sky may not be the main attraction. It also doesn't have to be showcasing the Milky Way, star points, star trails, aurora, Zodiacal light etc. can all be very intriguing.