Components of the Universe
Note Section
The Solar System- One star
and everything that orbits it.
Planets: the larger bodies orbiting the Sun (or any other star)
The planets of our Solar System [& Pluto]
The biggest planet is….
-- but the biggest object in the Solar System, by far, is …..
Surface of Sun – Gas bubbles
Solar Flare – an explosive event on the Sun’s surface
Galaxy- Billions of stars bunched together.
The Sun is a star in the Milky Way Galaxy.
A spiral Galaxy seen Edge-on
-the actual 3D-shaped is like a pancake with a lump in the center
How big is a galaxy?
# of stars:
about a billion or so (smallest)
- up to 100’s of billions for
large galaxies
Diameter: Very large: what units of distance should
be used?
-- using miles gives awkwardly
numbers.
-- a larger unit is needed.
-- for example…..
Light-Travel-Time from the Earth
a.
b.
c.
d.
e.
f.
TO
the moon
the sun
Pluto
Alpha Cen
North Star
M31
TIME
1.25 sec
8.5 minutes
~6 hours
4.3 yrs
650 years
2.5 million yrs
DISTANCE
1.25 light-seconds
8.5 light-minutes
4.3 LY
650 LY
2.5 M. LY
..so just keep in mind that all of those units of length
are based on the speed of light;
- for example: 1 light-minute = the distance that light travels in one minute
The
“Milky Way”
galaxy is a
spiral galaxy.
The Sun is in
a spiral arm
half-way out
from the
center.
Map of Milky Way
Our Sun(yellow dot) is in a spiral arm, ½-way out
Galaxies contain more than just stars. The irregular-looking blobs are either
hot (pink) or cold (dark) interstellar clouds
Galaxies occur in galaxy clusters.
This is M31 (the Andromeda Galaxy)…
…. and friends (2 smaller neighboring galaxies)
- sort of a “triple galaxy”
 LMC
 SMC
 comet
The Universe is Everything- All the Galaxies
Distance = 500 million LY
What can you see with the naked eye? [outside of the Solar System]
- Milky Way stars! (meaning only stars in our own galaxy)
i.e., you cannot see any individual stars in any other
galaxy;-- they’re just too far and too faint
Note: Every star visible to your eye is part of the Milky Way!