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Transcript of The Sun
Our Sun is a Star *
Out of the BILLIONS of stars in the Milky Way Galaxy, our Sun is just one of them.
Each star has the potential to have planets orbiting around it. .... Solar Systems.
We just learned about our Solar System (MVEMJSUNp)
But let's take a closer look at our star - the Sun!
Origin of the Sun
Just like the rest of our solar system, the sun is about 4.5 Billion years old.
A swirling cloud of gas and dust, called a Nebula, is the birthplace of a star.
If this Nebula contracts due to gravity and begins to burn, a star is then formed.
The immense size and gravity of the star pulls nearby matter into orbits around it - the formation of the planets. This process is called "Planetary Accretion".
Throughout its life, sun is constantly burning Hydrogen. In this environment, Hydrogen fuses into Helium. This is called FUSION.
Light and Heat are given off (yay for us!)
Once the Hydrogen runs out, other elements in the sun will be burned until there isn't any more fuel.
When this happens.... the sun dies...
A Giant Furnace
But fear not!!!
The Sun is only about halfway through its life.
4.5 Billion down, 4.5 Billion to go.
Light and Heat
Remember that light from the Earth -> Moon or Moon -> Earth takes about 2.5 seconds to travel.
Light from the Sun to the Earth takes about 8 minutes and 20 seconds!
In other words, the light we see from the sun NOW actually left the sun 8 min and 20 sec ago!
WHOA, like Time Travel!
As we know, Earth is in the Habitable Zone. We're the right distance from the sun to support life. Not too hot, not too cold.
Because of the distance, some planets are either much hotter or much colder.
Here is how the sun could look from Pluto:
This also means for planets further out (MJSUNp), it takes even longer.
This also means when one is very far from a star, it can take MILLIONS of years for that light to travel. For example, the light we see from nearby stars is MILLIONS of years old - meaning that light left those stars before humanity existed ... some even during the time of the Dinosaurs!
As we know, planets rotate on their axis and revolve around the sun.
Suns do the same thing!!!
The Sun rotates on its axis about once every 27 earth days.
The Sun revolves around the center of the Milky Way Galaxy about once every 220 Milllion years <gasp!>
Let's take a closer look...
Layers of the Sun
Layers of the Sun
Photosphere: The innermost part of the sun's atmosphere and the only part we can see. 6,000 degrees Celsius.
Chromosphere: The area between the photosphere and the corona; hotter than the photosphere. 20,000 degrees Celsius.
Corona: The extremely hot outermost layer, extending outward several million miles from the chromosphere. 1,000,000 to 3,000,000 degrees Celsius.
Dark, cool areas that appear on the photosphere.
Always appear in pairs and are intense magnetic fields (about 5,000 times greater than the Earth's magnetic field) that break through the surface.
Field lines leave through one sunspot and re-enter through the other one. The magnetic field is caused by movements of gases in the sun's interior.
Sunspot activity occurs as part of an 11-year cycle called the solar cycle where there are periods of maximum and minimum activity.
Constant stream of electrically charged particles flying into space from the corona.
Reaches Earth within a few days.
In areas of sunspot activity, holes can open up releasing Solar Flares - violent explosions from the Sun.
Solar Flares are accompanied by the release of gas, electrons, visible light, ultraviolet light and X-rays.
When this radiation and these particles reach the Earth's magnetic field, they interact with it at the poles to produce the auroras (borealis and australis).
Solar flares can also disrupt communications, satellites, navigation systems and even power grids.