Type Ia supernovae are brilliant stellar explosions that can outshine an entire galaxy. They also have the useful property of always exploding with a similar brightness. This makes them useful in determining the distances of galaxies. By comparing the observed brightness of a type Ia supernova to its standard brightness, we can calculate the distance of the supernova, and the galaxy in which it resides. But while we know type Ia supernovae have a consistent brightness, we aren’t entirely sure why. Read more…
One Universe at a Time
One of the exciting aspects of astrophysics (and any area of science really) is how odd discoveries lead to new understanding. As a case in point, consider our understanding of the gas and dust in our galaxy. Gas and dust is often seen as an annoyance because it gets in our way. Observational astronomy would be much easier if it weren’t for all the gas and dust. Sure, gas clouds will sometimes collapse to form new stars, but beyond that it surely wasn’t doing anything interesting.
Our Sun (like other stars) is powered by nuclear reactions within its core. Part of the way we know this is through the observation of solar neutrinos. When solar neutrinos were first observed, the levels observed were less than predicted by about a factor of three, which came to be known as the solar neutrino problem. Since then we’ve come to understand that neutrinos have mass, and can change between flavors (electron, muon, and tauon), which solves the solar neutrino problem. Our neutrino detectors are good enough that we can now produce neutrino images of the Sun, such as the image above, and the rates of neutrino emission are in good agreement with solar core models.
Bok globules are small, dense clouds of gas and dust, typically only about a light year across. They are thought to be dust clouds undergoing the early stages of gravitational collapse, on their way to becoming a stellar nursery. Since they are in the early stages of gravitational collapse, they haven’t formed any protostars to start generating heat. So they tend to be very cold as well as dense, meaning they don’t emit much light on their own.
One of the big questions about the universe is whether there is intelligent life “out there”. We know that life evolved here on Earth, so it seems possible that similar life could evolve on other worlds. Whether they would survive and evolve what we would consider intelligence is another matter. There have been some estimates made on just how likely this might be, such as through the Drake equation. There is a lot about these estimations that are purely speculative, but we do know that Earth-like planets (at least in terms of size and temperature) are likely very common. We also know the type of chemical elements life on Earth relies upon are common, and that life appeared on Earth relativity early in its history.