Who am I?

I need to make something clear. I am by no means an experienced astrophysicist. I’m not even in college trying to get a degree in astrophysics; I am a high school student who has stumbled upon this world by myself and I have explored this world with my own hands.

I am Yang Jie Lin Hu, a 17-year-old aspiring astrophysicist who is still in high school and who one day decided that he wanted to turn his eyes to the cosmos and try to label it with numbers. He wanted to understand, both mathematically and fundamentally, what the world was like. Guided by youtube videos, a textbook, pencil and paper, and curiosity, I have self-taught astrophysics on a fundamental level. I will update this page as I continue to explore this new field.

This article / resource is my own reflection on my own studies, with the desire to help anyone who is also interested in this type of direction.

Image on celestial mechanics: the orbits of the celestial bodies

Astrophysics at a glance

Astrophysics, as a course, is not astronomy . Yes, they are both related to the stars and the cosmos, and if you like one, you will probably like the other, but the key difference is that as a course / degree, astrophysics is mathematics . There is a substantial amount of math calculation, equation recall, and estimation. Be prepared for that if you are willing to take this course.

The main topics:

  • Celestial coordinates, celestial mechanics, binary systems
  • Telescopes and observation
  • Stars: spectra, brightness, interior, evolution, pulsation.
  • Galaxies and interstellar space
  • Our own solar system
  • Cosmology, which can be considered a separate course.
  • Computational / simulation astronomy, including software and computer modeling

I find the topics in bold the most interesting. They are more mathematical, more defined, more applied and less theoretical, less predictive, more like “physics” and less like just learning facts.

Starting off


“The best, the happiest, the coolest, and the most famous astrophysicists are all children at heart. So have fun, if you’re going to do it.” —Yang Jie Lin Hu, 2021

If you’re like me and don’t have access to a class you can sign up for, then your only option is to study astrophysics on your own :

  • Watch youtube videos. This is not a joke. Entertain yourself! Kurzgesagt , MinutePhysics , Veritasium , Myself .
  • Check textbooks. I highly recommend it as it is the way I learned the best. An Introduction to Modern Astrophysics by Bradley W Carroll and Dale A Ostlie is particularly good (for the first ~ 10 chapters at least).
  • Find some lectures. This will require you to do some searching, but here are some of the resources I found: CourseArena , Yale .
  • Join a Discord server. It sounds stupid, but this is how you can stay up-to-date with competitions, ask other capable people questions, and also get helpful tips for learning yourself: Astro Olympiads .
  • Solve problems . For example, MIT .

About you

  • Calculus is not required, but having learned it is highly recommended .
  • Physics experience required: energy, momentum, strength, etc.
  • Don’t be discouraged if it is difficult to understand. This is a college course for a reason.

Written by Yangjie Lin Hu