Some cool facts about the Universe

The solar system:

Sun is the most perfect sphere ever observed in the universe.Light is created inside sun’s core, but it takes 30,000 years for it to reach sun’s surface i.e. time lag between production of light and emission from surface is tens of thousands of years.Sun appears white from space, not yellow.Helix nebula and Andromeda galaxy would be clearly visible in the sky given- no light pollution, no decrease in brightness over distance. Andromeda would be six times the size of moon and helix nebula about the size of moon. Google the pictures of Andromeda and helix and imagine how beautiful it would look. :-) (The brightness of Andromeda in this image is highly exaggerated)

Mercury is the only planet smaller than a natural satellite of any planet. (Ganymede>Mercury)Venus is the hottest planet in solar systemnot mercury.Earth is the densest planet in solar system.Earth is the most massive solid body in solar system. List of Solar System objects by size. (Sun, Jupiter, Saturn- Gaseous || Uranus, Neptune- Icey)Moon is not as close as we think. (To-scale image of earth and moon)

Though outer planets are way bigger than the Earth, gravity is almost the same,except for Jupiter.Average distance between asteroids in asteroid belt is almost 1 million kms- 3 times dist. between earth and moon. Not so crowded as shown in pictures!Distance between Sun and Jupiter is almost equal to distance between Jupiter and Saturn.Mass of Jupiter=2.5 times ‘Mass of all planets combined’Neptune was mathematically predictedbefore it’s discovery.

Rest of the universe:

Average temperature of the universe or temperature of empty space is 2.73 Kelvin.But lowest temperature recorded in universe is on earth. Scientist have achieved up to 10^(-10) Kelvin. This is pretty cool.The Milky Way is 100,000 ly across. Neighbor Andromeda is 200,000 ly across. Largest galaxy IC 1101 is 6,000,000 ly across.Largest structure in universe is supposedly 6 to 10 billion ly across- Hercules-Corona Borealis Great Wall Not only there are super huge structures but universe has supervoids too. Largest void in space is >1 billion ly in diameter. It is void of not only matter but also dark matter- It is a cold spot.Fastest Pulsar star spins with 716 rotations per second. Hence it’s equator speed is very close to the speed of light.Gamma Ray Bursts (GRBs) are considered as the most violent type of explosions in the universe.Supernovae can briefly outshine the parent galaxy and emit more energy that the star has emitted over it’s entire lifetime.

Some interesting facts about the Milky Way galaxy

1. A 250-Million-Year Orbit



On Earth, a year is determined by the length of time it takes the planet to orbit the Sun. Every 365 days, we’re right back where we started, generally speaking. It makes sense then that our entire solar system is similarly orbiting the black hole at the center of the Milky Way. It just takes a little longer, to the tune of 250 million years for each rotation. In other words, we’ve made about a quarter of a single orbit since the dinosaurs died.
Descriptions of the solar system rarely mention that it’s spinning through space just like everything else. We’re actually traveling at about 792,000 kilometers (483,000 mi) per hour relative to the center of the Milky Way. To put that into a more easily relatable example, that speed would take you around the Earth in just over three minutes. Each time the Sun makes it all the way around the Milky Way, it’s known as the galactic year, or cosmic year. It’s estimated that there have been only 18 galactic years in the history of the Sun.

2.Twin Galaxies



While the Milky Way might be unique in many ways, it’s safe to say it’s not exactly rare. We already mentioned that spiral galaxies are one of the most common types in the universe; add to that the fact that there are around 170 billion visible galaxies, and it wouldn’t be a stretch to imagine that there could be a few galaxies out there very similar to our own.
But what about one that’s almost an exact replica of ours? In 2012, astronomers discovered a galaxy that shares a likeness with everything we know about the Milky Way. It even has two small satellite galaxies orbiting it, perfectly corresponding to our own Magellanic Clouds. And that’s rare—only 3 percent of spiral galaxies have companion galaxies like that, and they don’t last long. The Magellanic Clouds will probably dissipate in a couple billion years, a leisurely afternoon on the cosmic time scale. To find another barred spiral with a supermassive black hole center that also has two satellite galaxies the same size as our own is highly unlikely, to say the least.
The galaxy is named NGC 1073, and it’s so similar that astronomers are actually using it to learn more about our own galaxy. Since we’re too deeply embedded for any kind of perspective on the Milky Way, NGC 1073 gives us that top-down view that we’ve always needed to fully study our own neighborhood.

3.Cosmic Warping



Although the Milky Way is a spiral by definition, that’s not an entirely accurate way to think about it—there’s actually a bulge at the center of the galaxy, so the whole thing sort of looks like a pancake with a pile of whipped cream on each side. The warped section is the result of hydrogen gas molecules stretching away from the two-dimensional plane of the spiral.
For years, astronomers were mystified by the seemingly inexplicable warping. By all logic, the gas should be pulled toward the disk, not away from it. The more they studied it, the deeper the mystery ran—because the molecules in the warp are not only pulling away, they’re vibrating at a frequency of their own.
So what’s causing it? As far as we can tell, dark matter and a duo of small galaxies known as the Magellanic Clouds. When they’re put together, the Magellanic Clouds have about 2 percent of the Milky Way’s mass—not enough to affect it much. But when dark matter moves through the Clouds, it creates ripples that apparently affect their gravitational pull on the Milky Way. This strengthens the pull and entices the hydrogen away from the center of our galaxy.
And it gets even weirder. The Magellanic Clouds orbit the Milky Way, so as they make each revolution, the spiral arms of the Milky Way flap in response to their presence like a flag waving in the wind.

What is the hottest object in the universe?

On a typical day, one contender is the white dwarf that is at the heart of the Red Spider Nebula (NGC 6537).  The surface temperature of that star is around 300,000 K (540,000 R).  That's 50 times hotter than our sun.

Or you could go with a quasar, where the center burns 100 times as much energy as the Milky Way.  The gas around a quasar can reach a temperature of 80 million degrees.