PICTOR: Telescope Control
This website allows you to control a telescope that uses radio waves to observe certain space objects for free! There is also a guide on the website (you can find it by clicking here on the website). It offers lots of information that would help in using the telescope
NASA Solar System Exploration:
This is a website that was made by NASA that holds a ton of information about astronomical objects in our Solar System! It even shows lots of fun facts about certain planets, moons, asteroids, comets, and/ or meteors like how long a year is on that planet (in earth days/years). Also, it shows a visual representation of the Solar System as a whole, and it shows a visual representation of each and every planet on its own.
A Slower Speed of Light:
This is a game made by MIT Game Lab that helps people understand relativity in a better way. The quest in this game is to collect orbs that slow down the speed of light to reach the maximum speed reached by the character walking in-game. This would show some effects that might actually happen if this was possible in real life. You can read more about it on the website above.
CEARUN is a NASA database/program that has many thermodynamics-related uses. One of the popular things to use this program for is to analyze rocket fuel performance. The manual is on the site and youtube has many tutorials.