Here are some fascinating astronomy facts & theories about the universe
Some facts about the universe :
1. Our Sun is one of over 100 billion stars in the Milky Way galaxy, and the Milky Way is one of over 100 million galaxies in the universe.
2. The planet Saturn would float on water—it’s the only planet in our solar system that would.
3. The black hole in the center of the Milky Way galaxy is millions of times the mass of the Sun.
4. The planet with the hottest surface temperature is not Mercury, but Venus, because of the Greenhouse Effect of its atmosphere.
5. Earth is the only known planet with plate tectonics.
6. The Sun’s core releases energy equivalent to 100 billion nuclear bombs per second, and that energy travels thousands of years through its layers before it is emitted as heat and light to power the solar system.
7. Only one two-billionth of the Sun’s energy hits the Earth.
8. A car ride to the nearest star at 70 miles per hour would last over 356 billion years.
9. Ninety-five percent of the matter in the universe is either dark matter or dark energy that can’t be detected.
10. Venus spins backward on its axis compared to all the other planets in our solar system.
11. The other galaxies in the universe are moving away from us, and some are millions of light-years away.
12. Neutron stars, which are leftover from the deaths of massive stars in supernova explosions, are so dense that just a bowlful of neutron star material has more mass than the Moon.
13. Neutron stars also spin up to 500 times per second and are some of the fastest-spinning objects known to astronomers.
Theories about the universe :
Why is the universe the way it is? Over the years, scientists have explored many ways to explain the cosmos, leading to some crazy-sounding ideas…
The Big Splat
In the far future, galaxies will eventually drift so far apart that light from one can never reach another. In fact, as stars get old and die, there will come a time when there’s no light – or heat – left. The universe will be a dark, cold, empty void. It sounds like the end of everything, but according to one theory, it’s actually the beginning of the next universe in an endlessly repeating cycle. Remember the braneworld theory? What happens when one cold, empty brane collides with another – which, given enough time, it’s bound to do eventually. Cosmologists Neil Turok and Paul Steinhardt believe such a collision would generate enough energy to create a whole new universe. They call this the ‘ekpyrotic theory’, though physicist Michio Kaku has more evocatively dubbed it the ‘Big Splat’.
The holographic univers
Think of a security hologram. This is basically a two-dimensional object encoding a fully three-dimensional image. According to this theory, the whole three-dimensional universe may be ‘encoded’ on its two-dimensional boundary. It may not sound as exciting as living inside a simulation, but it has the advantage that it’s a scientifically testable theory – research in 2017 showed it was consistent with the observed pattern of CMB fluctuations.
The steady-state univers
The Big Bang is an evolutionary theory in which the universe changes in appearance as it expands. It was denser in the past, and it will become less dense in the future. Not all scientists were happy with that, so they came up with a way for the density to remain constant, even in an expanding universe. It involves the continuous creation of matter at the rate of about three hydrogen atoms per cubic metre per million years. This model fell out of favour with the discovery of the CMB, which it can’t easily explain.
The multivers
In the conventional view of the Big Bang, in order to explain the uniformity of the CMB, it’s necessary to postulate an early spurt of superfast expansion known as inflation. Some scientists believe that when our universe dropped out of this inflationary phase, it was just one tiny bubble in a vast sea of inflating space. In this theory, called ‘eternal inflation’,
other bubble universes are constantly popping up in other parts of the inflationary sea, with the whole ensemble making up a ‘multiverse’.The theory gets even stranger, because there’s no reason other universes should have the same laws of physics as ours – some might have stronger gravity, or a different speed of light. Although we can’t observe the other universes directly, it’s conceivable one of them could collide with our own. It’s even been suggested the ‘cold spot’ in the CMB is the imprint of such a collision.
Simulation theory
So far, all the theories have come from scientists – but here’s one from the philosophers. If all our evidence about the universe comes into our brains via our senses and scientific instruments, who’s to say it isn’t all a cleverly designed illusion? The entire universe might be nothing but an ultra-sophisticated computer simulation. It’s an idea that was popularised by the Matrix movies, but as outlandish as it sounds it’s taken seriously by some philosophers. However, it fails the test of a true scientific theory, because there’s no way it could be proved true or false.