Astro-Photography works only if you have a clear sky with very little clouds and little light pollution:

• On the Play store search for “long exposure” apps. DeepSkyCamera is one such app but there are more.
• Long exposure means that the camera shutter will be on for 5, 10 or 20 seconds. So, you can’t hold the camera in your hand because your hand will shake. You should put the phone on the ground, or use some support to tilt the camera (to point at a planet) and leave it there.
• Read this article on how to take photographs of planets and stars on a mobile phone.

You can also search Google for “astro photography with a smart phone” to learn more.