Solar eclipse: Everything you need to know
On Monday 21 August, millions of people will be able to witness one of the most amazing space events that can be seen from the Earth.
Across the US, lucky space watchers will be treated to an incredible total solar eclipse.
The last time the US witnessed an eclipse like this was in 1979, so everybody is understandably pretty excited!
This one is being called the Great American Eclipse 2017.
But it's not just the US that can enjoy this event. People all over the world will be watching too but they will only see a partial solar eclipse.
So what exactly is a solar eclipse, and what is the difference between a total and a partial one?
Read on to find out everything you need to know about this amazing event.
What is a solar eclipse?
A solar eclipse is when the Moon moves between the Sun and the Earth, so it blocks the Sun's light. This casts a shadow over part of the Earth.
The area on the Earth where the shadow directly falls, is the point at which people will be able to see a total solar eclipse.
This is because the Moon will be completely blocking the sun's light here, so it will fall dark for a short time just like it's night time - even if it is the middle of the day!
When the moon is directly in front of the Sun and covers it completely, people will see details of the Sun's atmosphere, which you can't usually see, glowing around the edge of the Moon. This is one of the reasons that a total solar eclipse is such a spectacular sight.
As the Moon moves, the shadow it casts moves across the Earth.
The route that this shadow takes is called the path of totality. Anyone watching the eclipse from an area that is on this path of totality will be able to see a total solar eclipse.
Outside of this area, you can still see the Moon blocking the Sun and casting a shadow, but it will only be blocking part of the Sun. So anyone in these areas will only be able to see a partial social eclipse.
This will look a bit like the Moon is 'taking a small bite' out of the sun!
How long will it last?
It depends on the eclipse, but generally during a total eclipse, the Moon will fully block the Sun's light for a couple of minutes.
Nasa has said that for this total solar eclipse, the longest period when the Moon will be completely blocking the Sun's light will be around 2 mins 40 secs.
This will take place in the US state of Illinois.
Nasa jets will be trying to chase the shadow to keep up with it and watch the eclipse for longer! They will have special cameras on the planes.
Who can watch this eclipse?
To see the total eclipse, you must be in the path of totality.
This eclipse's path of totality is quite thin - only about 70 miles wide. That's the same as the distance between Sheffield and Leicester.
The total shadow will cross the US from west to east, and pass through parts of 14 states - Oregon, Idaho, Wyoming, Montana, Nebraska, Iowa, Kansas, Missouri, Illinois, Kentucky, Tennessee, Georgia, and North and South Carolina.
So anyone who is in the right part of these states will have a brilliant view, provided the weather is good!
Everyone else in North America, and people in parts of South America, Africa and Europe will be able to see a partial solar eclipse.
How much they will see will depend how near they are to the path of totality - the closer the better!
So what will we see in the UK?
As the UK isn't on the path of totality, space fans here will see a partial solar eclipse.
That is because the shadow cast by the Moon won't fall directly over the UK.
So, if the weather is clear, people in the UK should be able to see the Moon move across part of the Sun.
But if it's cloudy, we may not see anything! Fingers crossed for a clear evening...
How can I watch it?
If you want to watch the partial solar eclipse in the UK, you must make sure you do it safely:
- Never look directly at the Sun: you can damage your eyes forever
- Even the amount of Sun peeking out from behind the Moon during an eclipse is enough to make you go blind, so you must never look at it directly
- Never look at the Sun through binoculars or a telescope.
- Don't look directly at the Sun through sunglasses, a camera or your phone camera - none of these suitably protect your eyes
In order to watch the eclipse happening, you will need special glasses. These are specially darkened and filtered to protect your eyes.
To find out where you can get your hands on a pair of these, you could speak to a local science museum, astronomy clubs or even your school.
They should be able to advise you.
Alternatively, you can use a special pinhole camera, which you can make easily at home.
Make sure that you are standing as far away from any artificial light - like bright houses or street lamps - as possible, as the darker it is where you are, the better your view will be.
It could be worth trying to get a glimpse using these methods - Britain won't be getting a total solar eclipse of its own until 2090!