WHAT CAN WE SEE IN THE NIGHT SKY?

Stars – large spheres of incandescent

(glowing) gas– Energy comes from nuclear fusion– H + H → He + energy (e=mc2)– E.g. Polaris, Sun, Betelgeuse,

Procyon, Regulus

Constellations– Regions of space– 88 regions– E.g. Ursa Major, Ursa Minor, Pegasus– Gemini, Leo, Capricornus, Scorpius

Asterism– Aster = star– Group of stars that make a pattern– Big Dipper, Little Dipper,

Great Square, Orion’s Belt, Summer Triangle

Galaxy– Cluster of billions of stars– Milky Way- our galaxy– Andromeda Galaxy (M31)

Spiral Galaxy NGC 4414 -

Nebula– Cloud of gas and dust in space– M42: Great Nebula in Orion (nursery

for stars)– Eagle Nebula

Eagle Nebula (M16) These eerie, dark pillar-like structures are

actually columns of cool interstellar hydrogen gas and dust that are also incubators for new stars. They are part of the "Eagle Nebula", a nearby star-forming region 7,000 light-years away in the constellation Serpens.

The picture was taken on April 1, 1995 with the Hubble Space Telescope Wide Field and Planetary Camera 2.

Dr. Jeff J. Hester, Dr. Paul A. Scowen, Arizona State University, STScI/AURA, NASA (1995)

North American Nebula(NGC 7000)

In Cygnus close to Deneb Emission nebula Discovered in 1700s by William

Herschel 50 ly across About 1500 ly away

Horsehead Nebula (Barnard 33)

In Orion Dark nebula 1500 ly away 3.5 ly across Discovered

1888

Ring Nebula (M57) In Lyra Planetary

nebula 2000-2500

ly away

Forms when star blows off gas- white dwarf star left behind

Crab Nebula (M1, NGC 1952) In Taurus Remnant of

supernova observed by Chinese in 1054

Hubble Space Telescope image of the Crab Nebula. High-energy particles accelerated by the Crab pulsar, a neutron star spinning with a period of 33 ms at the center of the remnant, cause the bluish glow of the interior. The outer filaments are the tattered remains of the star and consist mostly of hydrogen.

http://www.mpa-garching.mpg.de/~thj/popular/Crab_Nebula.jpg

Planets Bodies that revolve around the

Sun Have enough gravity to make

themselves round Cleared debris out of the region in

their orbit

Eight planets Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune

Could there be more planets that we cannot see?

Dwarf Planets Far from the Sun Have debris in their orbits ‘Kuiper Belt objects’ Examples: Pluto & Eris

Comets Orbit the Sun in eccentric paths ‘dirty snowballs’ E.g. Halley (1910, 1986, 2061)

Asteroids Large chunks of rock Live between Mars and Jupiter Largest: Ceres

Moons Satellites of a planet (the planet is the ‘primary’- it

goes around the Sun)