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 Moon has clearly seen some stuff. It’s visibly heavily cratered across it’s surface, which has remained unchanged since it’s surface solidified 4.2 Billion years ago. Think about that – the Moon has been the same, with the exception of cratering, for 4 Billion years. This is a stark contrast to the Earth, whose erosion and tectonic activity cause the crust to change on scales of a few hundred million years. Astronomers have worked hard to learn about the early solar system by looking at the Moon and its cratering patterns. Most of the visible craters on the Moon are...
A long time ago in a galaxy far, far away…. Not just the star wars intro, but a true statement if you’re an astronomer. You see, once we start to look deep in space at the more distant objects in the universe, we are actually looking deep in time as well. It all begins with a light year. A light year is not a measure of time, it’s a measure of distance. When you turn on the light in a dark room, the light appears to fill the room instantly. But it actually takes a small amount of time, as light has...
I was out on a sunny day a few weeks ago waiting for a bus, and as per usual I have my head up in space (I would say up in the clouds but that is too low for me). I noticed the Moon up in the sky, just past first quarter, and I was thinking about the angle of the illuminated side and how it related to some of the positions of the Earth and Sun in space. I wondered what information we could gather from the way it looked. It led me to this ‘illuminating’ post. I realized...
Every year, as the Earth revolves around the Sun, we pass an imaginary line directly from the Sun to Saturn. The Sun is on one side of us and Saturn is on the other. When two bodies are on opposite sides of the Earth like this we call it opposition. Saturn’s opposition for the year was on May 23rd, and even though it has been a few days, you can still see Saturn up pretty much all night. Along with opposition, we can clearly see the rings, but Saturn does wobble on a 29.5 year cycle, meaning there are times...
Today is a busy day in the world of astronomy and space news. The US Air Force has approved SpaceX for military launches, ending a ten year monopoly by Boeing and Lockheed-Martin. A black hole jet moving at nearly the speed of light is having traffic issues, resulting in knots of jet material rear-ending each other. An experiment in Quantum Mechanics has shown that reality simply doesn’t exist until we measure it. Finally, the Gemini planet imager has found a bright, disk-shaped ring of dust around the star HD 115600, which is being likened to the Kuiper Belt in the...
Ever heard the term ‘champagne flow?’ I’m not talking about a celebration, it’s actually a term in astronomy. When a cluster of massive stars form and ionize the surrounding hydrogen cloud, the hot gas propels itself through the layers of cooler gas at the cluster outskirts. When the hot gas finally bursts through to the vacuum of space, it flows rapidly like a newly opened bottle of champagne. This is exactly what’s happening in the cluster RCW 34, a young, gaseous cluster in the southern constellation Vela. The interesting thing about this cluster is that its nearly invisible in optical...
One of the largest and brightest star clusters in the Milky Way galaxy is the Arches cluster, and its easy to see why. Lying only 100 light years away from the supermassive black hole that lies in the heart of our galaxy, it formed in an incredibly dense environment. It lies 25,000 light years from Earth in the constellation Sagittarius, and contains thousands of massive stars, including 160 that are hot, young, and exceptionally more massive than the Sun. Only 1 in 10 Million stars in the galaxy are as bright as these massive central 160 stars. Though it is...
Auroras on Earth are caused by the ionization of atoms high in the atmosphere near the north and south magnetic poles. The solar wind flies toward the Earth and this harmful radiation is blocked and funnelled by our magnetic field, creating harmless, beautiful glows that remind us how close we came to total destruction, but were saved by our planet. Do other planets have auroras? Certainly! Jupiter and Saturn do, and even moons like Ganymede can have auroral activity. It really depends on the magnetic field. So how does a planet like Mars, with no magnetic field, have auroras? This...
When I do a planetarium show for an audience, and they see the night sky for the first time, I always ask them ‘What do you see?’ The response is the usual stuff – Stars, the Moon, maybe planets, or the Milky Way. But they seem to be missing the most important and largest part of the sky – the Darkness. Space itself. Stars light up the cosmos, but if there were no stars, would we think that the universe was empty? Perhaps, but if you can imagine this scenario, it gives you an important perspective when you want to...
