Download Distances in Space Vocabulary

U2: Astronomy Measuring Space
Distances
FLIP LESSON
On the Move

Nothing in space or our universe
stays still. Planets, moons, stars, and
galaxies are in constant motion. They
are moving due to the expansion of
the space in the universe. Space has
no known boundaries. The location of
Earth in space has to be relative to
other moving objects.
What does this mean?

The Earth represents a raisin in
rising bread dough. Each raisin
represents another object (stars,
planets, etc.) in space. Each object
in space will not move thru space but
expand with space like the raisins
move away from each other as the
dough rises. The raisins don’t move
on their own thru the rising dough.
Methods to Measure

Astronomers use several methods to
measure space distances. Lasers,
radio and radar waves have helped
us measure distances accurately. By
using the known distances of closer
stars, the distance to further stars
can be found. A measurement called
the parallax is used for this.
AU’s

Astronomers use units of measure
that express vast distance with small
numbers. For shorter measurements
in our solar system the astronomical
unit (AU) is used. One AU is about
150,000,000 kilometers or
93,000,000 miles. One AU equals
the average distance from the Earth
to the Sun.
Astronomical Unit (AU)

The average distance between
the Sun and the Earth.
1 AU is equal to 93 million miles
or 150 million kilometers
 An AU is a standard of distance
used within the solar system




Example:
Jupiter 5.2 AU
Light travels 1 AU in eight
minutes.
Sound travels 1 AU in 14 years
The Planets of Our Solar System
The Inner Planets
Sizes to Scale
Mercury
Venus
Earth and Moon
Mars
The Planets of Our Solar System
The Outer Planets
Jupiter
Saturn
Earth Included for Scale.
Uranus
Pluto
Neptune
SIZES AND DISTANCES IN THE SOLAR SYSTEM
Sizes
Diameters of Solar System Members:
Sun =
1,392,000 km
Mean Distance from Sun
Mercury =
Venus =
Earth =
Mars =
Jupiter =
Saturn =
Uranus =
Neptune =
Pluto =
4,878 km
12,104 km
12,756 km
6,794 km
142,984 km
120,536 km
51,118 km
49,530 km
2,304 km
57,900,000 km = 0.387 AU
108,200,000 km = 0.723 AU
149,600,000 km = 1.000 AU
227,900,000 km = 1.524 AU
778,300,000 km = 5.203 AU
1,427,000,000 km = 10.07 AU
2,871,000,000 km = 19.19 AU
4,497,000,000 km = 30.06 AU
5,914,000,000 km = 39.53 AU
Earth’s Moon =
3,476 km
Mean Distance from Earth = 384,400 km
Fun Facts About the Planets

18 Mercury’s would fit inside the Earth.

Venus is always cloudy.

Earth is the only planet we know with life.

Mars is red because it is covered with rust.

A storm (hurricane) on Jupiter can swallow 2 Earths.

Each season on Saturn is more than seven years long.

By the time you get to Uranus, you are only halfway to
Pluto.

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Neptune is the windiest planet, with winds blowing
over 1,000 miles-per-hour.
Pluto is a ball of ice and rock and is a dwarf planet.
Light Year

The light year is the most wellknown space distance unit used for
measuring distances outside our
solar system. It is equal to the
distance light will travel in one year.
Light travels 300,000 kilometers or
186,000 miles per second. A light
year (LY) is over 9,000,000,000,000
kilometers or 5,865,696,000,000
miles long.
Light Year (LY)

The distance a ray of light
travels in one year
The speed of the ray of light
would be equal to:
 7.2 AU per hour or
 300,000 km/sec or
 186,000 miles/sec.

http://planetquest.jpl.nasa.gov/SIMGuide2Galaxy_508.html
A Light Year is a standard unit of
measure for interstellar (star)
distances beyond the solar system.
 Milky Way Galaxy is approx. 100,000
LY across in distance


If the Sun and Earth
were 1 foot apart …
Proxima Centauri is 51 miles away!
Nearest star to the sun is
Proxima or Alpha Centauri C
approximately 4.22 LY
or 24 trillion miles
(6 trillion miles = 1 light year)
Proxima (or Alpha Centauri C) is a red dwarf
Alpha Centauri A is a yellow star
Alpha Centuari B is an orange star
Image 1
Parsec
For measuring distances between
galaxies, the parsec is used. A
parsec is equal to 3.26 light years.
 One parsec equals 206,000 AU’s or
about 30,000,000,000 kilometers.

Parsec

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One parsec is equal to 3.26 light
years
A parsec is a unit of measure
used for distances between very
far structures in the universe.
Example:
distances between galaxies
Andromeda and Milky Way

The Andromeda Galaxy (M31) is
slightly less than 800 kpc or
800,000 parsecs away from
Earth.
Approximately 2.4
million light years
Image 2
Time

It is important to consider time.
Time is related to distance. The light
you view from an object 100 light
years away left the object 100 years
ago. You are looking back into time
100 years. You see the object only
as it once was and where it was
years ago.

In the same way, our sun is 8.33
light minutes away. If the sun
exploded it would take us 8.33 min.
to see the explosion.