Page 27 - Life beyond the Karman

Could a Black Hole Destroy Earth?
Black holes do not go around in space eating stars, moons and planets. Earth will not fall into a black hole because none are close enough to the solar system for this to happen.
The sun will never turn into a black hole because it is not a big enough star to make one.
Satellites and telescopes travelling in space are used to learn more about black holes. These spacecraft help scientists to answer questions about the universe.
Dark matter
Dark matter is a component of the universe whose presence is discerned from its gravitational attraction rather than its luminosity.
Originally known as the “missing mass”, dark matter’s existence was first inferred by Swiss American astronomer Fritz Zwicky. In 1933, Zwicky discovered that the mass of all the stars in the Coma cluster provided only about 1% of the mass needed to keep the galaxies from escaping the cluster’s gravitational pull. The reality of this missing mass remained in question for decades, until the 1970s when American astronomers Vera Rubin and W. Kent Ford confirmed its existence by observing a similar phenomenon.
The mass of the stars visible within a typical galaxy is only about 10% of that required to keep them orbiting the galaxy’s centre. In general, the speed with which stars orbit the centre of their galaxy is independent of their separation from the centre; orbital velocity is either constant or increases slightly with distance rather than dropping off as expected. To account for this, the mass of the galaxy within the orbit of the stars must increase linearly with the distance of the stars from the galaxy’s centre. However, no light is seen from this inner mass; hence the name “dark matter.”
What is common about comets and asteroids is that they both orbit the sun and are far smaller than the planets.
Meteors, meteoroids, and meteorites
Meteors, meteoroids, and meteorites all relate to the flashes of light called “shooting stars” sometimes seen streaking across the sky.
They are more or less the same object, but they are called different names, depending on their location or position.
Meteoroids are objects in space that range in size from dust grains to small asteroids.
When they enter another planet’s atmosphere at high speed and burn up, the fireballs or “shooting stars” are called meteors.
When a meteoroid survives a trip through the atmosphere and hits the ground, it is called a meteorite.
They are also called “space rocks” because they are mostly pieces of other bodies that have been broken or blasted off, some from comets, others from asteroids, and some even from the moon and other planets.
This is why some meteoroids are rocky, while others are metallic, or combinations of rock and metal.
Meteor Showers
Several meteors per hour can usually be seen on any given night. When there are a lot, they are known as a meteor shower.
Meteorites that fall to Earth represent some of the original, diverse materials that formed planets billions of years ago.
By studying meteorites, we can learn about early conditions and processes in the solar system’s history including the temperature and age of different planets that formed them.
LIFE BEYOND THE KÁRMÁN LINE - OUTER SPACE
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