Why does the Universe expand the way it does? Why does it accelerate? Einstein’s equations offer an explanation of gravity that works on the scale we know, but do they work on the grandest scales of space and time? Humanity now has a way to find out. The General Theory of Relativity predicts the behaviour of gravity, and includes a term known as the cosmological constant. Einstein added this term to make the universe static and unchanging, as he believed it was. But when the expansion of the universe was discovered by Edwin Hubble, Einstein regarded it as ‘the greatest blunder...
A pretty cool result came out of Cornell University this week, showing that Mars was struck by a pair of ancient asteroids that caused massive tsunamis. Not only is it the first evidence of a tsunami event on another world, but it proves that Mars once had a large ocean. The study looked at ancient shorelines between the lowlands and highlands of Mars, where the ocean-land boundary would have been. Two massive impacts, a few million years apart, extended the shorelines and caused turmoil with the Martian climate at the time. “About 3.4 billion years ago, a big meteorite impact triggered...
Looking at the universe in radio waves is a fascinating sight. For one, the radio sky is very weak; If you placed your cellphone on the Moon facing back at Earth, it would be brighter than all other radio sources in the entire sky by a factor of a million. But as with every other part of the electromagnetic spectrum, it has scientific value in studying the sky. Over the past decade, astronomers have been identifying several Fast Radio Bursts (FRB), short bursts of radio waves from different places in the universe that last for a few short seconds. These are...
Is this a giant hole in space? I show a picture similar to this as I ask this question to students and audiences that I host in my planetarium. Most people answer that it is a black hole, or dark matter, or dark energy, or something strange like that. But the amazing thing is that it is actually a thick cloud of dust that is opaque, letting no visible light from the distant stars pass through. The funny thing is that the cloud is transparent in infrared light, but in the visible spectrum it highlights something interesting about the universe:...
Around 470 Million years ago, two asteroids collided in the asteroid belt between the planets Mars and Jupiter. This sent fragments everywhere, and millions of years later these fragments moved into the inner solar system, many of which struck the Earth as meteorites. Recently, in Jämtland county, Sweden, a team of geophysicists has identified a pair of impact craters that were formed at the same time, likely from two separate impactors. One of the craters is a massive 7.5 Km across, while the other is smaller at 700 meters. This is the first time a double impactor has been scientifically confirmed on Earth....
A couple of days ago, the still-active Cassini spacecraft orbiting around Saturn performed a flyby of the small Moon Hyperion, taking high resolution photos of the surface, and showing the sponge-like surface of the moon in a different light. Hyperion is a moderate 250 kilometers wide, yet it doesn’t tug very hard on Cassini. Performing measurements of its surface gravity, Cassini has shown that the moon is mostly empty space, similar to a pumice stone on Earth. The odd shapes of the craters are thought to be a result of this. When an impactor hits Hyperion, it blows the material...
The science of Astronomy goes far beyond what humans can see with our eyes. The visible part of the spectrum has taught us so much, but when we look at all photons across the spectrum of light, we find exponentially more powerful methods for discovering the mysteries of the universe. Radio waves, yes the same ones that bring you music in your car, are found throughout the universe in very interesting environments. Radio waves often trace the most powerful objects in the universe, such as super-massive black holes, quasars, and other types of active galactic nuclei. Humans see visible light...
