Dark matter could be almost anything. With little data other than how much total dark matter mass exists, we can’t decode much about what individual chunks of dark matter might be made of. I’ve talked before about Massive Compact Halo Objects (MACHOs) and Weakly Interacting Massive Particles (WIMPs), but these are just two possibilities. Other theorists have talked about Modified Newtonian Gravity (MNG), where gravity may work differently on the grand scale than it does on our small Earth scales. Or perhaps it’s something I haven’t seen before. Maybe what we call dark matter is just a large population of ancient black holes....
Gamma rays are the most powerful form of electromagnetic radiation in the universe. With wavelengths as small at atoms, they usually result from the most powerful interactions known, such as the collision of two particles, or the release of energy from the accretion disk of a black hole. But there is another potential source of gamma rays that has not yet been confirmed: Dark Matter. The leading candidate for dark matter is the theorized Weakly Interacting Massive Particle (WIMP), though it is not as wimpy as its namesake suggests, making up 5 times as much mass as the visible matter...
We know that galaxies like our Milky Way are far more massive than we can see. The dark matter in the Milky Way makes up 90% of it’s total mass. Another way of saying this is the Mass to Light ratio, comparing the total mass inferred by the rotation speed of the galaxy to the total mass of stars in the galaxy. This ratio, M/L, for the Milky Way, is about 10. But for a galaxy cluster, the M/L ratio is more like 100. Galaxy clusters are not just dense collections of stars and massive galaxies, they are also immense...
The Andromeda Galaxy is the closest large spiral to our own Milky Way, and the only major Galaxy moving toward us. Turns out its on a direct collision course, but we still have 3.5 Billion years to prepare, so its not exactly pressing news. On the plus side, studying Andromeda allows us to infer properties of more distant galaxies, and it gives us a map of what our own Milky Way Galaxy may look like. Astronomers using the Hubble Space Telescope have discovered a giant halo of gas around Andromeda, and the Milky Way may have a similar one. By...
Every single massive galaxy has a black hole at its center, and bigger galaxies have bigger black holes. It almost seems like a natural progression, with a bigger galaxy meaning more stars and material to feed a bigger black hole. However, most of that material doesn’t make it to the central black hole. So how does a massive galaxy with hundreds of billions of stars spread out over hundreds of thousands of light years contribute to a black hole that at most is solar system sized? The answer might lie in another elusive and enigmatic gem of the universe: Dark...
When the temperature is just right, and the sky is clear, you can see some amazing phenomenon from the Sun. It isn’t your eyes playing a trick on you, it just means you’re seeing the right conditions for a really amazing experience. Sun Dogs, known scientifically as Parhelia, typically appear as two bright patches on either side of the Sun. Occasionally they reveal rainbow colours in their pattern, but can be quite bright. They are most easily visible when the Sun is low in the sky. Sun Dogs are made from the refraction of ice crystals in the upper atmosphere....
