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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

Units In Space

Larger units are used to measure distance in space

thank you matt c

Light-years are used

to measure even greater distances than AUs

Light-Years

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

Just how big is space?

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?

Techniques for Indirectly Measuring Distance

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

Steps of triangulation

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

  • Astronomical Units (AUs) and light-years are used to measure distance in space

  • Triangulation and parallax can be used to determine the distance to any visible object

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

Measuring Distances in Space

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?

point A

point B

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