Where Is Our Solar System Located within the Galaxy

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Slide 11

Looking toward the Galaxy Center in Sagittarius – Visible Light

Slide 12

Looking toward the Galaxy Center in Sagittarius – Infrared Light

Slide 13

The Galactic Center – Zooming in, in Infrared Light

Shows very high density at the Center.

Slide 14

Galactic Nucleus – in Radio Waves

Sagittarius A (Sgr A) is at the Galaxy Center, and is very bright in Radio Waves. SNR = Supernova Remnant.

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Galactic Nucleus – in Infrared

Stars orbiting a MASSIVE object that cannot be seen – a 4 million solar mass BLACK HOLE – where the Sgr A radio source is located.

Slide 16

The Black Hole Area at the Center of our Galaxy might look something like this.

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Orbits of Stars in Different Parts of Our Galaxy

NGC 4144, very similar to the Milky Way.

Slide 18

Our Galaxy rotates, and the center rotates faster than the outer parts do – Kepler’s 3rd Law !

NOT like this.

Like THIS.

Slide 19

The Galaxy’s Rotation Curve – shows there’s Dark Matter beyond the visible edge of the Galaxy.

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How Much Dark Matter Does Our Galaxy Have?

The stars and other objects that give off radiation account for only 10% of the Galaxy’s total mass.

The other 90% of our Galaxy is made of stuff that we can’t see at any wavelength of radiation – so we call it “Dark Matter.”

Dark Matter forms a sphere around the Galaxy, at least 12 times farther from the center than we are.

We don’t know what this Dark Matter is, but it does have gravity.

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WHAT DID YOU THINK?

How many stars does the Milky Way Galaxy contain?

The Milky Way has about 200 billion stars.

Where is our Solar System located in the Milky Way Galaxy?

The Solar System is in the Orion Arm, about 26,000 light years from the center of the Galaxy.

Is the Sun moving through the Milky Way Galaxy and, if so, how fast?