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One AU is the distance from the Earth to the Sun
1 AU = 150 million km
From the Earth to the Edge of the Solar System
50 000 to 100 000 AUs
AU
(Astronomical Units)
An Astronomical Unit (AU)
is a unit used to measure distance
within the Solar System
Even AUs become meaningless for measuring greater distances outside the solar system
Larger units are used to measure distance in space
thank you matt c
Light-years are used
to measure even greater distances than AUs
These units are called
AU's and Light-years
A light-year measures distance, not time
Light moves at a speed of
300 000 kilometres per sec.
One light-year is how far light can travel in one year
300 000 km × 60sec × 60min × 24hr × 365d
= approximately 9.5 trillion km
One light-year is approximately 9.5 trillion km
Light travels faster than anything else we know.
but light from this galaxy must travel for
2.5 million years to reach Earth.
Andromeda Galaxy
2.5 million light-years away
We've looked at units for measuring
vast distances in space.
But, HOW do we measure something
that cannot be reached?
we better get a good mark on this prezi
The universe is astronomically big.
Distances between planets and stars are unimaginably far
They cannot be measured
in regular units such as metres.
What is
Triangulation?
It is a method that uses
a scale diagram of a triangle
to indirectly measure
distances to stars
Parallax
Parallax is the apparent shift of an object against a
stationary background,
Scale of objects in the universe
caused by a change in the position of the observer.
Triangulation and Parallax
Parallax comes from the greek word
Which means "Alteration"
(parallaxis)
The observable universe is about
100 000 000 000 000
000 000 000 000
If humans are 1
on this scale,
can be used to measure distances to any visible object that we cannot reach
Here is a tree.
Step 4. Draw a scale diagram with the baseline and angles
=3.7 cm
35°
30°
12 cm
3.7 cm x 1000 = 3700cm = 37m
Ratio = 10m : 1cm
Step 3. Measure the angle
from the opposite end of the baseline
to the tree
This person wants to measure the distance to the tree.
Step 2. At the end of the baseline,
measure the angle to the tree with a protractor
35°
30°
Step 1. Measure and draw a straight baseline (ex.120m)
In conclusion,
The distance to the tree is 37 meters.
Triangulation and parallax
are only accurate
when objects
being measured are within
500 light-years away
the easier it is to measure the angles.
The longer the baseline of the triangle,
The calculations become more accurate.
Thank you for watching.
Astronomers can use the Earth's orbit and parallax
to calculate distance to stars
Q. Why do astronomers use Earth's full orbit as their baseline?
A. They must use the longest possible baseline to get the most accurate measurements.
With these angles, you can use
triangulation to find the distance
to the star
Take a good look at this star
angle B
angle A
Baseline
Meaghan Soloway
Jenna Fitzsimmons
By Eunsol Kim
You have just observed parallax
This star never moved.
It appeared as if it had shifted
because of the change in the observer's position
Did you notice the shift?