Why does the Sun seem red near the horizon? Why does the Moon do the same? We know the Moon isn’t actually changing colour, and the Sun isn’t either. So what is happening to the light? The first thing to note about the image above is that the size of the Moon doesn’t change, showing that the well-known ‘Moon Illusion,’ where the Moon appears larger near the horizon, is just that – an illusion. The second is of course the gradual change in hue as the Moon rises. The reason for the colour shift really has nothing to do with the Moon...
I’ve written many times about the power of looking at different wavelengths of light to study different properties of the universe. From a visualization standpoint, there are other techniques that give you additional power when imaging. More than just the wavelength of light you’re using to show the detail, you can choose the range of wavelengths to bring forward certain features while suppressing others. The aptly-named spaghetti nebula, shown above, is a great example of this. A supernova remnant that covers the constellations Taurus and Auriga, the nebula is very large in the sky, covering three full moons worth (love that unit...
When could the Moon possibly be brighter than the Sun? The Sun is much bigger, produces energy, and gives all the energy needed for life on Earth. But if you look at the sky in gamma rays, the highest energy photons on the electromagnetic spectrum, you’ll see the Moon more easily than the Sun. Why? The Moon is the brightest gamma ray source in the sky, because it has no atmosphere or magnetic field. Essentially it has no protection from the dangerous cosmic rays that are constantly zipping through space. When they hit the Earth’s atmosphere they create a cosmic...
I love false-colour images. They reveal detail that you can’t see in real life, but they also highlight things in an artistic way. For me it’s an excellent marriage of art and science, and as a communicator it helps me get concepts across in an accessible way. So when I saw the APOD image of Saturn from earlier this week, I had to discuss it. Saturn never has looked this way, and it never will. The colours are vivid and unrealistic, but they show the differences in three distinct but close wavelengths of light on the electromagnetic spectrum. All of...
Black holes are the most extreme phenomena known in the universe. They are the absolute limit of what gravity and space-time can be twisted into. It’s no surprise that some of the most massive and advanced telescopes in the world are tasked with studying their properties and how they interact with their environment. But maybe there’s a way for you and I to see what a black hole can do, and all we need is a moderate 8 inch telescope and our eyes! Even though black holes generally give off tons of radiation, we need to observe them 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...
The first exoplanet ever discovered was 51 Pegasi b in 1995. It kicked marked the slow beginning of what would soon become the ‘exoplanet gold rush.’ It meant that for the first time, we had the technological capacity to discover new worlds, and science fiction soon became science fact. 51 Pegasi b was also a very strange planet. A massive Jupiter sized world orbiting very close to its home star. On one hand it was this characteristic that made it much easier to detect. On the other, it showed us that we did not understand planetary system formation as well...
Cassiopeia A is the expanding remainder of a massive star that exploded 340 years ago in he constellation of Cassiopeia (hence we call it Cas A for short). As the star erupted, hot radioactive material was shot out in all directions, churning up the surrounding outer debris, before the star finally tore itself apart. Simulations of supernova explosions have found it difficult to model the extreme conditions during this process, even when using the world’s best supercomputers. So what are astronomers missing? By studying recent supernovae like Cas A, astronomers can study the processes that formed these massive expanding shock waves, leading...
You may know that the Universe is much more complex than we know. If you look at nearly anything in a different wavelength of light, new details can pop up that you’d never expect. Astronomers today use all the wavelengths of light to study the Universe. Even the most seemingly boring objects can come to life in different wavelengths. As a prime example, take the Moon. Now I don’t find the Moon boring at all, in fact it’s quite interesting and has a lot of influence on the Earth, so its fun to talk about. But when we look at...
I’ve seen a lot of lovely images from the Spitzer Space Telescope. It takes infrared images and can see the fine structure of galaxies, where stars are forming and where they are not forming. The photos paint a picture of the history and evolution of a galaxy. The latest image released last week shows some amazing features. The Cyan light in the image is a combination of blue and green coloured light representing infrared wavelengths of light at 3.4 and 4.5 microns. This wavelength shows the stellar population in the galaxy. The red light is representing dust features that glow...
