Download Exploring Space What’s Out There?

Exploring The Night Sky:
What’s Out There?
Celestial Objects
• Any object in space is a celestial object
comets
planets
stars
moons
asteroids and
meteoroids
Planets
• 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
Inner Planets
Mercury, Venus, Earth, Mars
• Terrestrial (solid cores and
rocky crusts)
Outer Planets
Jupiter, Saturn, Uranus, Neptune
• Gaseous (called “Gas Giants”)
• Mostly gas, ice and dust
So, what makes it a Planet?
• Remember, a planet must:
1.
2.
3.
Orbit a star (like the sun) and no
other celestial object
Contain enough mass so gravity
pulls it into a round shape
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)
Stars
• 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!
The Sun
• 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!
Features of the Sun
• Sunspots = Dark
area on the sun’s
surface that is
cooler than the
surrounding areas
• Solar Flare = Large
explosions of gas
and charged
particles
Auroras
• 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
Why is our Sun Important?
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
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
Moons
• 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
The Moon
• 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
So, what else is out there?
• 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
Video of 2013 Russian Meteor
So, just how small are we?
• 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
Elliptical
Galaxy
Lenticular
Galaxy
Irregular Galaxy
Spiral Galaxy
Astronomical Measurements
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!!!
And, because you asked…
A Black Hole….
• Black hole = a
region of space
with gravitational
pull so strong
that even light
cannot escape
What would it feel like
to go through a black
hole?
(click to find out!)
Do you think other
life exists in the
universe?
(click)