The Sun

The Sun is a star. Not just any star. The Sun is Our Star. It is the centre of the Solar System and all of the objects in the Solar System orbit it. The Sun is the primary energy source for the Earth and without it, we wouldn’t be here.

The Sun Credit: NASA

The Sun is big but it’s just one of the estimated 150 – 250 billion stars in the Milky Way galaxy. It is approximately 1.39 million km in diameter and you could line up 109 earths across its face. It is a giant ball of hot plasma. The Sun is made up mainly of hydrogen and helium. In the past, scientists didn’t know what powered the Sun. At one point, scientists guessed that maybe the Sun was made of coal. However, when they calculated how long a piece of coal the size of the Sun would take to burn, they realised that it couldn’t be coal.

What they didn’t know, is that the light and heat energy that is produced in the Sun, is produced by a process called nuclear fusion, which happens deep inside the star. Nuclear fusion, at a very basic level, is where two atoms of hydrogen fuse to form a helium atom and in the process releases some energy. The Sun converts about 600 million tonnes of hydrogen into helium every second. This energy from the core of the Sun travels up through various layers before radiating out into space in the form of light and heat. It can take thousands of years for light to get from the centre of the Sun and escape into space.

The Sun is around 4.6 billion years old and formed from a giant cloud of gas and dust. It is about half way through its life. Eventually the Sun will run out of hydrogen. At that point it will turn into a type of star called a red giant. The Sun will swell and eventually engulf Mercury and Venus. Scientists are not sure for certain if Earth will also get swallowed by the Sun. Even if it survives, the heat from the much closer Sun will have baked the Earth dry. We don’t need to worry about that though, because that is around 5 billion years away!

The Sun is the brightest object in the night sky. You should never ever look at the Sun as it is so bright it will cause permanent eye damage. Pointing any sort of cameras or equipment at the Sun is also dangerous as it could damage the equipment. It is possible, with correct equipment to observe the Sun safely. Astronomers that do observe the Sun look for features such as sunspots, flares, coronal holes and prominences. There are a number of solar telescopes around the world that observe the Sun and also a fleet of spacecraft that observe and study the Sun. The first of which was Pioneer 6 in 1959.

Studying the Sun and monitoring it, is really important. Solar weather, which is variations in activity on the Sun, can have a wide variety of impacts here on Earth. Solar storms can cause power outages, communications outages, damage satellites and put astronauts in danger. Right now there are two spacecraft situated between the Earth and Sun, called SOHO (Solar and Heliospheric Observatory) and SDO (Solar Dynamics Observatory). Both of these spacecraft monitor the Sun 24 hours a day. The Parker Solar Probe is the latest NASA probe to explore the Sun. It launched in August 2018 and will be operational for at least another 6 years. The main purpose of the Parker Solar Probe is to monitor the Suns atmosphere which is also called the Corona.

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