Yesterday I wrote about how interstellar clouds of methyl alcohol can be induced to create microwave laser regions (astrophysical masers). This was due to a stimulated emission of light in excited atoms. As strange as that seems, you can also have the opposite effect, or stimulated absorption.
The Pleiades Parallax
The Pleiades is an asterism in the constellation Taurus. It’s an open cluster of bright stars, which makes it very easy to find in the night sky. So easy that it’s often confused with the big dipper. It also happens to be about 380 light years away. Or 450 light years, depending on which measurement you trust.
Bok Globules
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.
Alien Glow
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.
Red Dawn
If you’ve ever watched a sunrise or sunset, you’ve seen how the Sun appears deep orange, or even red when low in the sky. In the middle of the day the Sun appears merely yellow. So why does it appear different colors at different times of the day? The answer lies in how light interacts with our atmosphere.
Mars Opposition
No, Mars will not appear as big as the Moon tomorrow night. I’m sure that’s a fact most of you already know, but the rumor has made its annual return to social media, so I figure it’s worth stating again. The image you see above, as well as other similar images, is fake.
The Reveal
An occultation is where one object passes in front of another from your vantage point. It is similar to an eclipse or transit, but in this case the occulting object completely blocks the more distant object. Typically occultations occur when the moon occults planets, or when solar system objects occult stars.
Hidden Variables
In the constellation of Ursa Major (of which the Big Dipper is a part), in the crook of the tail (or bend in the handle) is a double star known as Mizar and Alcor, seen above. These stars are visually separated just enough to be distinguishable to the naked eye. Distinguishing them requires good vision, and they were sometimes used as a test of visual acuity.
Seven Sisters
The seven sisters, also known as the Pleiades, is an open cluster of stars, meaning it is a loosely bound star cluster. It is distinctive in the sky because its brightest stars are brilliant blue stars. At least six stars in the cluster are easily seen with the naked eye. With a pair of binoculars or a small telescope, you can see hundreds of stars in the cluster, which makes it an excellent object for amateur viewing.