Page 8 - Life beyond the Karman

Solar system
The solar system consists of our star, the Sun, and everything bound to it by gravity – the planets Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune; dwarf planets such as Pluto; and asteroids, comets, and meteoroids.
The Sun
The sun holds the solar system together, keeping everything in its orbit. It is a 4.5-billion-year-old star – a hot glowing ball of hydrogen and helium at the centre of our solar system. The sun is about 93 million miles (150 million kilometres) from Earth, and without its energy, life as we know it could not exist.
The sun is the largest object in our solar system. Its volume would need 1.3 million Earths to fill it.
The sun is the centre of the solar system, and its gravity holds this system together. Everything in the solar system revolves around it, including planets, asteroids, comets and even space debris. The sun is made of super-hot, electrically charged gas called plasma that rotates at different speeds on different parts of the sun.
The hottest part of the sun is its core, where temperatures top 27 million degrees Fahrenheit (15 million degrees Celsius). The sun’s activity, from its powerful eruptions to the steady stream of charged particles it sends out, influences the nature of space throughout the solar system.
At its equator, the sun completes one rotation in 25 Earth days while at its poles, it rotates once on its axis every 36 Earth days.
Above the sun’s surface are its thin chromosphere and the huge corona (crown). This is where we see features such as solar prominences, flares, and coronal mass ejections.
Nothing could live on the sun, but its energy is vital for most life on Earth. It keeps our planet warm enough for living things to grow and gives us light so we can see planets and exoplanets.
“The sun is the centre of the solar system, and its gravity holds this system together. Everything in the solar system revolves around it, including planets, asteroids, comets and even space debris.
Of the eight orbiting planets the inner, rocky planets are Mercury, Venus, Earth, and Mars. The outer planets are gas giants Jupiter and Saturn and ice giants Uranus and Neptune.
Beyond Neptune, a newer class of smaller worlds called dwarf planets reign, including Pluto. Many more planets have been discovered beyond our solar system, orbiting other stars. Scientists call them exoplanets (exo means «from outside»).
Sunspots
Sunspots are magnetic storms on the fluffy surface of the sun which appear as darker areas. On average, a sunspot can be hundreds of thousands of miles long and many are larger than the Earth. Sunspot temperatures are cooler and produce far less light, so they appear dark against the background of the Sun.
Solar flare
A solar flare is a sudden and rapid increase in brightness in a region on the surface of the sun. It occurs when the magnetic energy built up on the surface of the sun is suddenly released. The energy released during a typical solar flare is very strong. It is equivalent to millions of 100 megaton hydrogen bombs exploding at the same time.
The Corona
There is a region around the sun, extending more than a million kilometres from its surface, where the temperature can reach two million degrees. This region, called the solar corona, is where the solar wind originates. The corona has been found to emit X-ray radiation (the corona is a plasma; at temperatures greater than a million degrees a plasma will radiate a lot of X-rays). The corona can be seen during solar eclipses, when the main radiation from the sun’s surface is blocked by the passage of the Moon or with special instruments.
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LIFE BEYOND THE KÁRMÁN LINE - OUTER SPACE
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