Space

Our Galaxy- The Milky Way Galaxy

• Our galaxy - the Milky Way Galaxy - is a spiral galaxy with arms extending from the center like a pinwheel.

• Our solar system is in the Orion arm of the Milky Way.

• Our Sun is one of about 100 billion stars in the Milky Way.

• And our galaxy is just one of roughly 100 billion in the visible universe.

Questions

• What is at the center of the galaxy?The Galactic Center harbors a variety of intriguing puzzles, including a strangely

quiescent supermassive black hole, a collection of wispy magnetic filaments, a few

dense stellar superclusters which host mysterious and massive stars, a star with a tail, and a family of gas streamers spiraling

toward a central dark mass.

Our Solar System

Only one star ; Earth is the Third Planet

And just to give you an idea…

And just to give you an idea…

And just to give you an idea…

And just to give you an idea…

And just to give you an idea…

The SunThe only STAR in our solar system!

NewSong

OldSong

The Sun

The Sun- Did you know?

Age: 4.6 Billion YearsType: Yellow Dwarf (G2V)Diameter: 1,392,684 kmCircumference at Equator: 4,370,005.6 kmMass: 1,989,100,000,000,000,000,000 billion kg (333,060 x Earth)Surface Temperature: 5500 °C

The Sun’s Revolution

• The Sun and the entire solar system orbits around the center of the Milky Way galaxy. The average velocity of the solar system is 828,000 km/hr. At that rate it will take about 230 million years to make one complete orbit around the galaxy.

Question

• How long does it take for light from the sun to travel to Earth?

The sun's light takes about 8 minutes to reach the Earth after it has been emitted from the sun's

surface. The time it takes for light to reach other planets/objects in our Solar System (not the Milky

Way, which is our galaxy) varies from about 3 minutes for Mercury, to about 5.3 hours for Pluto.

Sun Facts:

• Eventually, the Sun will consume the Earth:When all the Hydrogen has been burned, the Sun will continue for about 130 million more years, burning Helium, during which time it will expand to the point that it will engulf Mercury and Venus and the Earth. At this stage it will have become a red giant

Sun Facts:

• The Sun will one day be about the size of Earth:After its red giant phase, the Sun will collapse, retaining its enormous mass, but containing the approximate volume of our planet. When this happens, it will be called a white dwarf.

Earth Facts:

• Earth is the third planet from the Sun and is the largest of the terrestrial planets(inner planets with rocky/hard surface). Unlike the other planets in the solar system that are named after classic deities the Earth’s name comes from the Anglo-Saxon worderda which means ground or soil. The Earth was formed approximately 4.54 billion years ago and is the only known planet to support life.

Earth Facts:

Mass: 5,972,190,000,000,000 billion kgEquatorial Diameter: 12,756 kmPolar Diameter: 12,714 kmEquatorial Circumference: 40,030 kmKnown Satellites: 1Notable Satellites: The MoonOrbit Distance: 149,598,262 km (1 AU)Orbit Period: 365.26 Earth daysSurface Temperature: -88 to 58°C

Earth Facts:

• The Earth’s rotation is gradually slowing:This deceleration is happening almost imperceptibly, at approximately 17 milliseconds per hundred years, although the rate at which it occurs is not perfectly uniform. This has the effect of lengthening our days, but it happens so slowly that it could be as much as 140 million years before the length of a day will have increased to 25 hours.

The Moon

Moon Facts:

• The Moon (or Luna) is the Earth’s only natural satellite and was formed 4.6 billion years ago around some 30–50 million years after the formation of the solar system. The Moon is in synchronous rotation with Earth meaning the same side is always facing the Earth. The first unmanned mission to the Moon was in 1959 by the Soviet Lunar Program with the first manned landing being Apollo 11 in 1969.

Moon Facts:

Circumference at Equator: 10,917.0 kmDiameter: 3,475 kmMass: 73,476,730,924,573,500 million kg

(0.0123 x Earth)Average Distance from Earth: 384,400 kmLength of Orbit: 27.3 Earth daysSurface Temperature: -233 to 123 °C

Moon Facts:

• The rise and fall of the tides on Earth is caused by the Moon:There are two bulges in the Earth due to the gravitational pull that the Moon exerts; one on the side facing the Moon, and the other on the opposite side that faces away from the Moon, The bulges move around the oceans as the Earth rotates, causing high and low tides around the globe.

Moon Facts:

• The Moon is drifting away from the Earth:The Moon is moving approximately 3.8 cm away from our planet every year. It is estimated that it will continue to do so for around 50 billion years. By the time that happens, the Moon will be taking around 47 days to orbit the Earth instead of the current 27.3 days.

Moon Facts

• The Moon has no atmosphere:This means that the surface of the Moon is unprotected from cosmic rays, meteorites and solar winds, and has huge temperature variations. The lack of atmosphere means no sound can be heard on the Moon, and the sky always appears black.

Our Solar System

What’s with Pluto?

Only one star

What is a planet?

• A planet is an object that orbits a star• Large enough to become rounded by its own

gravity• Able to clear its own orbit of objects, such as

asteroids, meteoroids, other space junk!

What’s with Pluto?To be a planet…

1) The object must be in orbit around the Sun. – Well, Pluto does that!

2) A "planet" has to be big enough that gravity squeezes it into a round shape. – Well, Pluto does that.

3) A planet must be big enough that it's gravity removes other objects that occupy the same orbit. – But Pluto does not meet this criterion.

Poor Pluto…

Also, Pluto has an orbit that is eccentric (oval-shaped), yet the other 8 planets have circular orbits. This is something that has bothered astronomers for a long time.

So, Pluto is considered to be a DWARF PLANET

Comets

• Mass of frozen gas, cosmic dust and ice crystals

• Circle sun in long, narrow orbits, orbit begins just past Neptune

• Some leave their orbits and if they come near the Sun it “boils” away, forming a tail pointing away from the sun

• If Earth passes through comet dust, it can be seen in the sky as a “meteor shower”

Comets

Asteroids

• Metallic, Rocky objects in space• No Atmosphere• Move in independent orbits around Sun• Too small to be classified as planets• Some are the size of a small building• Most are less than a kilometer wide• Smaller than half the size of the Moon

Asteroid

Asteroid Belt