CMB - or ‘Cosmic Microwave Background’ - is the thermal radiation filling the observable Universe - the echo of the start of the Universe. Currently, we can see 380,000 years after ‘The Big Bang’; that’s around 13.37 billion years ago!
It is the radiation left over from an early stage in the development of the Universe; when the Universe was young, before even stars and planets, it was a lot smaller and a lot hotter, filled with a glow and a fog of hydrogen plasma. As it expanded, both grew cool enough that protons and electrons could form neutral atoms, and so did not absorb the radiation. This meant the Universe became transparent instead of being an opaque fog.
The glow is nearly uniform in all directions, but the tiny variations show a pattern which is equal to what would be expected of a hot gas that has expanded to the current size of the universe. From the data taken, a map of the Universe is formed; the WMAP image.
Did you know: there is thought to be a missing planet where the asteroid belt is!
The Titius-Bode Law is a formula which correctly predicts the distances of planets from the sun, when the subsequent factor of two is entered into the formula:
a = 0.4 + 0.3 x k
This works brilliantly, apart from the fact that it appears there should be a planet between Mars and Jupiter - right where the asteroid belt is. It was thought at one point there there may have been a planet there which was destroyed by a collision, but now it is assumed that the gravity from Jupiter, prevented a planet forming from the fragments of the belt.
Did you know: Apple deleted an entire galaxy!
The source of Apple’s famous wallpaper is a picture of the Andromeda galaxy, but they photoshopped out several smaller galaxies, including the M110, just to clean it up a bit!
Did you know: Comets are actually made of ice.
Their bright tails of light happen when the comet approaches the inner Solar System and solar radiation causes the materials within to leave the nucleus. Along with dust and and gas, these cause an atmosphere around the comet. This is what is visible from Earth, reflecting the light of the Sun; it is not in fact the comet that you see, it is actually its atmosphere.
Scientists are trying to work out the number of galaxies in the whole of our universe, and so far they have surveyed about 3% of our sky. They have found around 3 million galaxies in that section of the sky, so if the number of galaxies is the same around the whole of the sky, there is around a hundred million galaxies in the universe.
There are around a hundred million stars in a galaxy.
So, this means that there are around a hundred million galaxies, in each of which are a hundred million stars. This means there are 10,000,000,000,000 (or ten quadrillion) stars in the universe. Each star has “on average … at least 1.6 planets.”
That’s 16,000,000,000,000 (16 quadrillion) planets out there. And people say we’re the only ones to exist.
There’s actually something called the Drake Equation which estimates the number of extraterrestrial civilisations in just our Milky Way galaxy, and you can find more information about that here.
This is an infrared picture of the galaxy. It’s 300 billion light years across. Scientists can zoom into the centre of the galaxy, and see high velocity stars orbiting a dark space, showing the location of a black hole. It’s hot gas orbiting a massive black hole (called an accretion disk), and so the light coming from that region shows astronomers precisely where the black holes are. A few pixels on your computer screen cover an area 27 million miles across, and the black hole they orbit is 4 million times the weight of our own sun.
This is why I want to take astrophysics. Because I want to try and understand stuff which no one has yet to understand. I want to find out the very meaning of our world; what made it, why it came to be and exactly what is in everything. It’s literally going to the edges of the universe.