Exploring The Night Sky: What’s Out There?

• Any object in space is a celestial object

Celestial Objects

planets cometsasteroids and meteoroids

moonsstars

• Planet = a large, round, celestial object that travels around a star

• Orbit = the path that a celestial object takes around another object

• Solar system = the sun and all the celestial objects that travel around it

Planets

• Recall that there are 8 planets in our solar system

Planets

Inner PlanetsMercury, Venus, Earth, Mars

• Terrestrial (solid cores and rocky crusts)

Outer PlanetsJupiter, Saturn, Uranus, Neptune• Gaseous (called “Gas Giants”)• Mostly gas, ice and dust

• Remember, a planet must:1. Orbit a star (like the sun) and no

other celestial object2. Contain enough mass so gravity

pulls it into a round shape3. Clear other celestial objects out

of its orbit

• A dwarf planet does not clear its orbit (sorry, Pluto )

• Planets are not luminous (they only reflect light, and do not produce it)

So, what makes it a Planet?

• A star is a massive collection of gases that emit large amounts of energy– Stars are luminous (they

produce their own light)

• Our sun has a mass 340,000X larger than the Earth!

Stars

• Nuclear reactions occur in the core of the sun– Atoms of hydrogen (H) fuse to form atoms of helium (He)

• These reactions release huge amounts of energy

• The sun’s core reaches temperatures of ~15 million °C!

The Sun

http://www.google.ca/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=0DnnPvl2W6SU1M&tbnid=Vcs_Zq33II7m1M:&ved=0CAUQjRw&url=http://www.dailymail.co.uk/sciencetech/article-437806/Death-throes-mighty-star-captured-hubble-telescope.html&ei=CNVLUdiwEciQyQGE-IH4BQ&bvm=bv.44158598,d.aWc&psig=AFQjCNG1Nk5C2vGwenEKkrrAVBIDPRnt7g&ust=1364010578913189

• Sunspots = Dark area on the sun’s surface that is cooler than the surrounding areas

• Solar Flare = Large explosions of gas and charged particles

Features of the Sun

• Auroras are produced when charged particles released by the sun come into contact with Earth’s magnetic field and atmosphere– Aurora Borealis at the North Pole– Aurora Australis at the South Pole

Auroras

The Sun is important because:– It is the source of

energy for ALL living organisms on Earth

– Energy from the sun drives the climate and weather patterns we experience on Earth

Why is our Sun Important?

But what about other stars out there?

• Our Sun is the closest star to Earth(This is why it appears to us to be the brightest and largest star)

• Constellation = group of stars in the sky

Constellations – Big Dipper & Little Dipper (Ursa Major & Ursa Minor)

Constellations - Orion

Constellations - Cassiopeia

• Moon = a celestial body in orbit around a planet– Moons are not luminous– Reflect light from the sun

• Scientists believe that 4.6 billion years ago Earth collided with an object the size of Mars– Molten rock from Earth

flew out into space, forming the moon

Moons

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• The moon has a nearly solid interior

• Craters are created when asteroids collide with the moon

• The moon is the only celestial object that humans have landed on

The Moon

• Asteroids = small, rocky, irregular shaped celestial objects

• Meteoroid = piece of rock or metal smaller than an asteroid– Streak of light when a meteoroid enters

Earth’s atmosphere is called a meteor

• Comet = large chunk of ice, dust and rock that orbits the sun– Glowing head and long tail

So, what else is out there?

Video of 2013 Russian Meteor

• Galaxy = a huge grouping of stars, planets and dust clouds

• Galaxies are HUGE! – Contain between a billion (1,000,000,000) to a trillion

(1,000,000,000,000) stars!! – We are part of the Milky Way Galaxy

So, just how small are we?

Spiral Galaxy

Irregular GalaxyLenticular

GalaxyElliptical Galaxy

Objects in space measured using:• Astronomical Units (A.U.) = The

distance between the Earth and the Sun; about 150 million km

• Light years (ly)= the distance that light travels in one year; 9.46 X 1012km or 63241 A.U.

• Earth’s closest star (after the Sun) Proxima Centauri is still 4.2 ly away!!

• Earth’s next closest galaxy is thousands of light years away!!!

Astronomical Measurements

• Black hole = a region of space with gravitational pull so strong that even light cannot escape

And, because you asked…A Black Hole….

Do you think other life exists in the universe?

(click)

What would it feel like to go through a black hole?

(click to find out!)