365 Days of Astronomy - Weekly Edition

After the cosmic microwave background radiation was released, the Universe returned to darkness, cloaked in this clouds of primordial hydrogen and helium. Gravity pulled these vast clouds into the first stars, and then the first galaxies. This is Cosmic Dawn, and JWST will help us probe this mysterious time in the Universe.

Astronomers first noticed the strange behaviors of rotating galaxies almost 100 years ago, suggesting there’s an invisible dark matter hold them together with gravity. Or maybe we just don’t understand how gravity works at the largest scales. Observations are much better now, and astronomers have found examples of galaxies that are almost entirely made of dark matter. Does this tell us anything?

In 2017, astronomers detected the gravitational waves and electromagnetic radiation from colliding neutron stars. This had been long theorized as one of the causes of a certain type of gamma-ray burst. By studying the event and its afterglow, astronomers have learned a tremendous amount about the formation of the heaviest elements in the Universe.

Last week we talked about rogue stars. This week we’re going to take things up a notch and talk about an even more extreme event. Rogue black holes. Astronomers recently discovered a supermassive black hole on an escape trajectory, leaving newly forming stars in its wake. It’s wonderful, terrible, nightmare fuel.

Most stars in the Milky Way are trapped in here with us, doomed to orbit around and around and around. But a few have found a way out, an escape into the freedom of intergalactic space. How do stars reach escape velocity, never to return?

Okay sci-fi writers, today we’re going to give you a guided tour of building planets. How they form, how they grow, and how things can go horribly horribly wrong. [Editor’s Note: Google HL Tau, click on the Wikipedia link and see planets forming!]

Whenever astronomers discover something surprising, the answer often turns out to be dust. Dust obscuring our view, dust changing the polarity, dust warming things up, dust cooling things down. It’s always dust. Until it isn’t.

We’ve spent a lot of time gushing about Saturn’s rings, but there are other places with ring systems. And not just Jupiter and the ice giants, but asteroids, dwarf planets, centaurs and even exoplanets. Today let’s gush about them!

Ice is ice, right? You know, what you get when water freezes. Well, maybe here on Earth. But across the Universe, water can be squeezed together at different temperatures and pressures, leading to very different structures. Today we’ll talk about the different forms that ice can take.

The asteroid apocalypse is one of those existential crises that keep astronomers up at night. But the DART mission showed us that we can push an asteroid off its trajectory if we have enough warning. Today we’ll talk about how humanity is building early warning systems to give us time to respond to a dangerous asteroid.

If you’re in dark skies and look up, you’re certain to see a satellite. Lots of them. But how can you know which one you’re seeing, and how can you improve your chances of a sighting? Today we’ll talk about how to see satellites, or avoid seeing them.

We’ve talked about the rising problem of space junk. Okay, we know it’s an issue. So what can be done about it? Today we’ll talk about ideas to remove space junk, making sure space is open to use for the centuries to come.

Last week we talked about the laws that govern space exploration. This week the rubber hits the road. What are the consequences for actually breaking these rules? Are they really going to stop anyone?

Streamed live on Feb 13, 2023. The Universe was inaccessible for most of human history, but the first tentative steps to space in the 20th Century made humanity realize that science fiction was becoming science reality. New rules would have to be written to govern how we used this limitless expanse. Today we’ll talk about the Outer Space Treaty of 1967.

It’s been over 20 years since astronomers first discovered that the expansion of the Universe is accelerating thanks to dark energy. And in these decades, astronomers still don’t have much evidence for what could be causing the increased expansion rate. Maybe there’s something else going on to explain it.