Asteroids are rocky worlds revolving around the sun that are too small to be called planets. They are also known as planetoids or minor planets. There are millions of asteroids, ranging in size from hundreds of miles to several feet across. In total, the mass of all the asteroids is less than that of Earth's moon.
Despite their size, asteroids can be dangerous. Many have hit Earth in the past, and more will crash into our planet in the future. That's one reason scientists study asteroids and are eager to learn more about their numbers, orbits and physical characteristics. If an asteroid is headed our way, we want to know that.
Ever since Earth formed about 4.5 billion years ago, asteroids and comets have routinely slammed into the planet. The most dangerous asteroids are extremely rare, according to NASA.
An asteroid capable of global disaster would have to be more than a quarter-mile wide. Researchers have estimated that such an impact would raise enough dust into the atmosphere to effectively create a "nuclear winter," severely disrupting agriculture around the world. Asteroids that large strike Earth only once every 1,000 centuries on average, NASA officials say.
On Feb. 15, 2013, an asteroid slammed into the atmosphere over the Russian city of Chelyabinsk, creating a shock wave that injured 1,200 people. The space rock is thought to have measured about 65 feet (20 m) wide when it entered Earth's atmosphere.
When an asteroid, or a part of it, crashes into Earth, it's called a meteorite
A rogue planet is a planetary-mass object that orbits a galactic center directly. Such objects have been ejected from the planetary system in which they formed or have never been gravitationally bound to any star or brown dwarf.
Nibiru is a hypothesized planet located on the outer edges of our solar system that allegedly completes one orbit around the sun every 3,600 years and theorists believe that its gravitational influence has disrupted the orbits of other planets in the solar system over hundreds of years ago and that Earth’s time is nigh.
Hypervelocity stars are stars that are moving faster than other stars in the galaxy or universe.
Hypervelocity stars can be caused by
being ejected from the centre of the galaxy after getting too close
being part of a multiple star system where one star has gone supernova and push the other star on it journey. science videos. universe size comparison
The stillness of the night sky is deceiving. Because of the sheer vastness of space, stars appear unmoving like celestial fixtures. In actuality, though, they're zipping through the cosmos - some at ridiculously high speeds: thousands, and even tens of thousands of kilometres per second. international space station
Some astrophysicists have suggested that, in principle, stars could go even faster - even as fast as light. Such stars may even harbour planets, prompting speculation that they could serve as intergalactic transport for alien life.
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