I’m going to come right out and ask the burning question: Is Pluto a Planet? No. At least under the current definition. So the question becomes “Should Pluto be a planet?” That answer is a bit more complicated. Let’s look at the history. Discovered by Clyde Tombaugh in 1930, Pluto was initially considered the ninth planet of our Solar System. It was part of an intense search that follows back all the way to the discovery of Uranus and the orbital calculations that led to the discovery of Neptune. Even after Neptune’s discovery, gravitational perturbations pointed to a ninth planet,...
Alliteration is accessible to all! Okay I’m done. Start some science! Really done this time. Today’s double post covers the smallest of stars, still larger than most planets, and the only weather Mercury will ever have. Humans are naturally interested in the extremes, the biggest, smallest, fastest, hottest, coldest, and every other characteristic outlier. With stars, being so huge and powerful, we are often more interested in the largest, hottest, and most energetic. Though on the opposite end of the spectrum, Cambridge University astronomers have discovered the smallest star in the known universe. The star, a red dwarf, has the...
As I was watching the grand finale of Cassini and listening to the mission team talk about the accomplishments of the mission, I learned a little bit about propellors. Not your typical airplane propellor, but the name used to describe this fascinating feature in Saturn’s rings. Seeing Saturn’s rings from afar, or even relatively close with Cassini, we see the rings as perfect. How do we end up with strange features and imperfections like this one? Looking elsewhere in the rings, we can find clues. The first clue is the namesake of the mission itself. The Cassini spacecraft was named for...
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...
Mercury crossed the face of the Sun this past Monday, a relatively rare event that occurs only a dozen (give or take) times a century. Being able to see it in real time was excellent, but seeing the photos taken by professionals and amateurs alike made the event truly memorable. And look! The International Space Station flew by. Compare this to 2012’s transit of Venus and you get a sense of how much closer to Venus the Earth is than Mercury. In both cases, the most beautiful thing is that you get a sense of just how immense and powerful...
It hasn’t been found yet – let me make that clear. But with evidence that it should exist, astronomers are looking more closely at the proposed planet nine and how it might have formed, and how it could have ended up in such a distant orbit. When you start to think about how a planet ten times the mass of Earth could have ended up more than ten times as far from the Sun as Neptune, a few scenarios pop into mind: It was formed in the inner solar system, where interactions with gas giants or another star pulled it out It formed...
Hubble just discovered the newest moon in the solar system, a tiny rock orbiting the dwarf planet Makemake, far beyond the orbit of Neptune. The new moon is about 250 Km across, compared to the 1,400 Km wide Makemake. It orbits in approximately 12 days, and has an edge on orbit, making it difficult to spot. “Our preliminary estimates show that the moon’s orbit seems to be edge-on, and that means that often when you look at the system you are going to miss the moon because it gets lost in the bright glare of Makemake,” said Alex Parker of...
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...
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...
The most violent single event in the universe is the death of a massive star, a supernova. We have seen several different types, though the common element is a massive explosion, taking a star hiding amongst the background into an eruption that outshines it’s entire host galaxy. We have seen the brightness grow and fade over the duration of a supernova event, but we have never seen one just as it’s starting. Until now. Would you ever have thought that the Kepler space telescope, a planet hunter that continuously observes stars, could see supernovae? The key is in the words ‘continuously observed.’ By keeping...
