A direct consequence of Einstein’s theory of general relativity, and an observational way to prove it, is gravitational lensing. It requires a powerful gravitational source to work, such as a galaxy or cluster of galaxies. It works in a similar way to a lens of glass, where rays of light are bent toward a single source, increasing the brightness. In this case, instead of glass, the bending of the rays is due to the curvature of space. Light rays coming from the source would otherwise miss Earth, but instead are bent toward us when there is a massive object in front of it. It’s...
If a supernova were to go off somewhere in our galaxy, the minimum safe distance for Earthbound life would be about 50 light years. Any closer than that, and we would experience an intense blast of high energy radiation and an eventual shower of radioactive particles. It would be like nuclear bombs were set off all around the Earth, causing little destruction but a lot of radioactive fallout. Supernovae are incredibly powerful to be able to cause such damage at 50 light years, but even at larger distances, we can see evidence of their effects here on Earth. A team of...
One of the most fascinating things happens whenever I show someone the planet Mercury in the sky. Their first reaction is to be surprised at how bright it is. Most people think of Mercury as a faraway planet, too close to the Sun to see at all. But in reality, Mercury is close to Earth, and when the angles are just right, it’s not hard to find. Mercury is 57 million kilometers from the Sun, more than a third of the way to Earth. We are also much closer to Mercury than we are to Jupiter and Saturn. When we see the...
In the post-Voyager era of deep space flight, spacecraft propulsion designs feel like science fiction. Instead of using rockets and a thermonuclear generator to produce heat, we have things like solar sails, laser sails, and ion propulsion. These all take advantage of the vastness of space to create a slow-but-continuous acceleration that can get spacecraft moving at incredible speeds. Of course, even at incredible speeds it will still take decades to reach other stars, but compared to Voyager, it’s a step in the right direction. If you want to get to the outer solar system quickly, try the Heliopause Electrostatic...
Neutron stars are the most extreme objects in the universe that have been proven to exist. Black holes are very likely, but we’re still not 100% sure about them. A black hole is like a giant squid in the ocean. We’re pretty sure they exist, but nobody has caught one. The neutron star on the other hand is like a blue whale, everybody knows they exist, and they are massive, rare, and beautiful. Of course, once we know something exists, the next logical step is to figure out how it behaves, to characterize and generalize it, and to identify where it’s...
Black holes form when a massive star runs out of fuel. Gravity causes the core to collapse down to an object so dense that light itself can not escape. In the Milky Way galaxy, there are expected to be over 100 Million black holes, though of course we can’t see them. The one we can see is the supermassive black hole Sag A*, lying deep within the core of the galaxy. But how did Sag A* form? Was it from the merger of many smaller black holes? Or is there some other process forming the most enigmatic objects in the...
There are eight planets in the Solar System. This statement makes a lot of people angry for several different reasons. The obvious group to respond with anger is the ‘people for Pluto,’ who have an unwavering dedication to the little planet that could. It’s scientifically recognized as a dwarf Planet, and is still one step up from a Kuiper Belt Object (KBO), so it’s doing well. Far beyond Pluto, in the outer recesses of our Solar system, you may have heard of a potential Super-Earth-sized Planet recently theorized by Konstantin Batygin and Mike Brown. This is the other reason people would...
There was a report about a month ago that a Fast Radio Burst (FRB) produced a repeating signal. This is big news because we really don’t know what causes FRBs, and once they have ended it can be difficult to trace their source. But a repeating signal means we can pinpoint their origin and potentially figure out their root cause. It’s no wonder the astronomical community was excited…and skeptical. Most of the FRBs that have been discovered were in archival data – data from past surveys that were given a closer look. Only a few have been seen in real-time, so when...
Have you ever seen the North star, Polaris? It’s decently bright and very close to the North celestial pole. Lining up with the rotation axis of the Earth, the North celestial pole is the point in the sky that never moves, day or night. If you know how to find Polaris, it becomes easy to find the cardinal directions and navigate by the stars. And finding it simply requires finding the big dipper, a bright and easily recognizable object. The same rules apply in the southern hemisphere. But even though there is no southern star, there is another fantastic object in the South that can guide you to the...
I feel like I’ve been covering a lot of stories on magnetic fields over the past few months. Fields around the Earth, the Sun, Mars, Jupiter’s Moons, and exoplanets are just some of the places in the universe where we are looking at magnetic field behaviour. The intention is to use our understanding of magnetism to figure out what is inside these worlds, and how they interact with their space environment. You would expect us to understand the Earth’s magnetic field and interior very well, after all, we are stuck here. But it turns out it’s very difficult to study the interior of...
