Mercury, the smallest planet in the solar system, and closest to the Sun, is only a little bit bigger than Earth’s Moon. But the Moon is comparatively reflective object. Mercury is thought to be made of the same rock as the Moon, so what is the difference? Why do objects in our Solar system have different brightnesses? The key is in a property called albedo. It’s basically how much light an object reflects, measured as a fraction. For example, the Moon reflects 12% of the light the Sun shines on it, so it has an albedo of 0.12. The albedo...
Our entire universe, from the tiniest atoms, to the structure of our experiential world, to the most massive galaxy clusters and the cosmic web, is dependent on a set of single properties, where small changes to these fundamental numbers would lead to a state where none of it could exist. Understanding these fundamental numbers is the key to unlocking the deepest secrets of the universe and answering the biggest questions of our existence. One of these numbers is the tiny difference in the masses of the proton and neutron. If it varied even a little bit in either direction, we...
When Canadian Astronaut Chris Hadfield was in space, on the International Space Station (ISS), he stayed there for six months, the standard length of stay for an astronaut. On the ISS, three of the six-person crew are replaced every three months. After returning to Earth, Hadfield could barely walk. He had lost bone density and muscle mass, his immune system weakened, cardiovascular functions slowed, and he produced less red blood cells. The lack of gravity is bad for humans, The longest a human being has ever been in space was Russian cosmonaut Valeri Polyakov, who was in space for a staggering...
We call it dark matter because it doesn’t give off light, right? Well there is a lot of matter than doesn’t radiate, but the difference is that whatever the stuff is that we call dark matter doesn’t interact with anything through the small-scale fundamental forces. The only way we have been able to detect it’s presence is through large-scale gravitational interaction. Dark matter is ‘dark’ because it doesn’t interact with anything in a way that lets us figure out what it’s made of. Well now that we’ve got that out of the way, we can look at the new...
A few months ago I talked about Astronomers seeing the gas cloud known as G2 passing the central black hole of the Milky Way, called Sagittarius A*, and how we had hoped to watch the black hole destroy it in order to learn about the behaviour of supermassive black holes. As we all sat and watched the passage of the cloud over the course of a few months, we were surprised to find that the cloud remained intact and passed straight by Sag A*. When we last checked in, the leading theory was that the ‘cloud’ actually was a dense...
How do we measure the rotation speed of a planet? Exactly as you would expect. Watch the surface, look for markable features, and time how long it takes until those features pass the same point again in the future. But how can we possibly nail down this information when the planet has little to no visible surface features. Gas giant planets are great examples of this. Jupiter is a bit easier since it has plenty of storms and separated cloud layers along the planet’s rotation axis, but the other three are much tougher. Aside from hard-to-spot features, gas giants also...
It’s difficult to determine the history of the Solar System. The planets have been in their current orbits for Billions of years, and any signs of prior activity or configuration has to come from leftover geologies of smaller, rocky worlds. It makes it especially difficult when the Billions of interloper asteroids and comets throughout history have to be accounted for, adding to the already complex task. But if there is one thing humanity has going for us it’s the ability to theorize, model, simulate, and test scenarios here on Earth. We can try new ideas and see if they match...
We have found evidence of ancient impacts all across the Earth, from the famous Chixulub crater in Mexico to the Sudbury Basin a little bit closer to my home. From Space the remains look nothing like craters, millions of years of sediment and growth hide the massive regions from obvious detection, but signs remain of these massive events, even after millions of years. This week, what is possibly the largest impact crater basin ever discovered has been found in central Australia. And it is thought to originate from the breakup of a massive 400 Km asteroid into two pieces that...
Yesterday I posted some of my own photos of the Moon and Mars in conjunction from the night before. Last night I went out again knowing that there was another planetary conjunction in the works. The Moon was now with Venus. People on the internet and in person were asking me “Mars? I thought the Moon was near Venus,” and “Venus? I thought the Moon was near Mars.” It really speaks to the fact that most people don’t realize how quickly the sky changes from the point of view of an Earthbound observer. So what happened between the Mars-Moon and...
Every 29.5 days we see a new Moon, or rather we don’t see it, since it’s lost in the glare of the Sun. But a few days after the new moon, we can see it slowly move away from the Sun and become visible after sunset, with the thinnest crescent growing a bit larger each night. You may have heard that Mars and Venus also live in the Western sky after sunset, with Venus moving higher and Mars appearing to double back toward the Sun, soon to be lost in the glare of our home star. Last night I was...
