Activities for STEM students

I think the simplest idea, but one that is very impactful, is starting some sort of blog. If you are that passionate about astronomy/astrophysics, read a bunch of articles and research papers on these topics, annotate them and understand each concept in-depth, and start talking about the new breakthroughs and cool aspects of whatever topic in your blog. Not only will this show that you've taken initiative, but colleges will see how interested you are in this subject matter (try to post a new article every other week). I know that research is something that high-achieving high school students want to experience, but starting a blog or some idea similar to this will show how you have taken initiative. Even if it's for some other topic, it is just as impactful. For example, I'm in the process of creating jump rope blog (even though I want to major in BME), so even a non-STEM idea can make the same impact (as long as one is extremely passionate about it)!

I wonder that too. Even without Covid most summer college activities are too expensive and require some special demographic.

The best suggestion I can give you is to join and/or start a club at your school that aligns with your interests. If it is challenging for you to find opportunities to participate in STEM activities, start them yourself.

I helped start a National Science Bowl club at my school! The competition already happened this year, but it's really fun and pretty easy to transfer to an online format. Each state does its own competition and then there's a national one if you win your state one. https://science.osti.gov/wdts/nsb

I feel like this is a pretty underrated extracurricular and I had a lot of fun doing it. I hope you consider it and do it!

I don't know much about this and I don't know how COVID-friendly it is, but the American Rocketry challenge could fit what you want to do. This is more engineering, but here it is if you're interested: https://rocketcontest.org/

Also remember that some places have online research opportunities. I was able to do a free summer program with RIT last summer and it was completely remote, so that was really nice (I got it through the Army Educational Outreach Program aka the AEOP, highly recommend you check them out). Check your local colleges or even ones further away and see if any professors have any labs that you can help out with remotely! Good luck with everything. :)