Section 2.5 - Interesting Astronomical Phenomena

There's a few other astronomical objects that are so interesting to me that I think they're worth discussing here, especially since they're sometimes in the news so I love talking about them in my regular blog posts.


I've discussed supernovae in prior sections already, the main point I want to make here is there's actually two broad types of supernovae, Type I and Type II. 

Type II is the one previously discussed - when a star with more than ~8x the mass of the Sun can no longer sustain nuclear fusion, the outer layers of gas suddenly collapse inward, compressing the core and rebounding back out in a spectacular explosion. 

Type I is more unusual because they occur only in binary stars (two stars orbiting each other) where one of the stars is a white dwarf. The white dwarf steals matter from its partner, gradually approaching the oh-so-important Chandrasekhar Limit. Once that limit is surpassed, the white dwarf explodes and completely obliterates itself. 

Credit: NASA

Because Type I supernovae always explode at the Chandrasekhar Limit, astronomers can use them as "standard candles" since they'll always explode with roughly the same amount of energy. They can then calculate how far away the supernova was depending on how bright it appears to us.

Next time you hear about a supernova, pay attention to whether it was a Type I or a Type II!


Quasars are the extremely bright centers of galaxies, formed by the supermassive central black hole that astronomers believe occupies the center of most galaxies. The black hole is surrounded by an accretion disk, the spiraling disk of matter being sucked into the black hole. As material is falling into the black hole, enormous amounts of energy are radiated out and easily detected. The most powerful quasars are thousands of times brighter than the entire Milky Way.

Credit: Wikipedia


Pulsars are highly magnetized neutron stars that emit electromagnetic radiation at regular intervals. They're often likened to lighthouses, because similar to how lighthouses emit a spinning beam of light that sweeps across a certain path, pulsars emit X-rays and gamma rays from its magnetic poles, and when those X-rays sweep across the Earth, we can measure them at regular intervals.

Fun fact, pulsars were first accidentally detected by Jocelyn Bell Burnell in 1967, and people thought the only explanation for such a strong electromagnetic burst at such regular intervals was alien technology signaling to us.
Credit: National Radio Astronomy Observatory

Book Recommendation

For a good primer on astrophysics and interesting astronomical objects, I recommend Astrophysics for People in a Hurry by Neil Degrasse Tyson