Space Heavenly Bodies Earth Space Science B Unit

Space: Heavenly Bodies Earth Space Science B Unit 3 lesson 4

Objectives • Measuring distance in space • Galaxies, quasars, and nebulae • Comets • Matter is fairly evenly spread throughout the universe, when viewed on a large scale. – Cosmological priniciple (know for test) Scientists calculate that there at least 100 billion galaxies in the observable universe, each one brimming with stars.

So, How do we Measure Distances in space? • For distance inside the solar system we often use astronomical units (AU) 1 AU = distance from Earth to the Sun (93 million miles) • For distances outside the solar system we use lightyear – the distance light travels in 1 year. – 1 light year = 9. 5 trillion km – Proxima Centauri is about 4. 2 light-years away

An interesting and strange thing about light speed. • The speed of light is 299, 000 km/sec. this is a constant. • Because of this – you can have twins and one twin were able to travel in a space ship close to the speed of light. Time for the traveling twin would slow down. • Thus the twin that stayed on Earth would be older. • This is because of E = mc 2 Einstein’s theory of relativity

What is a galaxy? • A galaxy is a huge group of stars, dust, gas, and other objects bound together by gravitational forces • The sun, along with an estimated 200 billion other stars, belongs to the Milky Way galaxy • What type of galaxy do we live in?

Milky Way Galaxy • The Milky Way is a spiral galaxy, a disc with an outer galactic halo and an extreme disc center. • It is about 100, 000 light-years in diameter • Our sun is about 26, 000 light-years from the center of the Milky Way • The center of the milky way has a very large black hole and rapidly orbiting stars. We are at the red circle

Spiral galaxies – consist of a central, dense area surrounded by spiraling arms

Barred spiral galaxies – have a bar-shaped structure in the center

Distances Between galaxies • • The distances between stars are 10, 000 times greater than the distances between planets The distances between galaxies are a million times greater than the distances between stars

Quasars • A quasar is a super dense mass of material that is the size of a solar system but as massive as millions of stars. • The can be brighter than 100 billion stars! • This is Quasar 3 C 273 photographed by the Hubble Space Telescope

Quasars • The central feature of a quasar is a super massive black hole. • The black hole has immense gravity and draws in mass from surrounding stars.

Nebula • A nebula (plural nebulae, nebulas) is a name given to galaxies, dust clouds, and star clusters. • The objects may be too far to discern what they are • Birthplace of stars

Butterfly Nebula Eagle Nebula Cat's Eye Nebula

Now let’s discuss something closer to Earth - Comets • Comets are cosmic snowballs of frozen gases, rock and dust that orbit the Sun. When frozen, they are the few kilometers across. • The solid part is the nucleus, When the ice vaporizes it forms a coma and a tail. Comet Halley Nucleus - 1986

Comets • Comets orbit the sun like planets. • When they get near the sun, they heat up and spew gases and dust into a glowing head that can be larger than a planet. This material forms a tail that stretches millions of miles. • Comet Hale-Bopp with a white dust tail and blue ion tail.

Where do comets come from? • Comets possibly originate in the Kuiper belt and there maybe many comets in the Oort cloud. Comet 67 P/Churyumov– Gerasimenko from a distance of about 8 km to the surface (2014)

How do they orbit? • Comets orbit the sun the same way planets and asteroids do – but in a more exaggerated path. • What shape is it’s orbit? A. Circle B. Oval C. Elliptic

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