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# Measuring Distances in Space - Triangulation and Parallax

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## Erin Reagh

on 12 January 2016

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#### Transcript of Measuring Distances in Space - Triangulation and Parallax

Even
AUs
become meaningless for measuring greater distances
outside the solar system
Units In Space
Techniques for Indirectly Measuring Distance
Measuring Distances in Space
Just how big is space?
The universe is
astronomically
big.

Scale of objects in the universe
Larger units
are used to measure distance in space

AU
(Astronomical Units)
An
Astronomical Unit (AU)
is a unit used to measure distance
within the
Solar System

One
AU

is the distance from the
Earth
to the
Sun
1 AU = 150 million km
Light-Years
A
light-year
measures
distance
, not time
One
light-year
is how far
light
can travel in
one year
Light
moves at a speed of

300 000 kilometres per sec.
300 000 km × 60sec × 60min × 24hr × 365d
= approximately
9.5 trillion km
One
light-year
is approximately
9.5 trillion km
Distances between planets and stars are unimaginably far

They
cannot be measured
in
regular units
such as metres.

These units are called
AU's, Light-years
and
parsecs
What is
Triangulation?
Parallax
we better get a good mark on this prezi
Light
travels
faster
than anything else we know.
Andromeda Galaxy
2.5 million
light-years away
From the Earth to the Edge of the Solar System

50 000 to 100 000 AUs
point A
point B
Take a good look at this star
Did you notice the shift?
You have just observed
parallax
This star never moved.

It
appeared
shifted

because of the
change
in the
observer's

position
Light-years
are used
to measure even greater distances than
AUs

but
light
from this galaxy must travel for
2.5 million years
to reach Earth.
We've looked at
units
for measuring
vast distances
in space.

But,
HOW
do we measure something
that
cannot be reached?
Triangulation
and
Parallax
can be used to measure distances to any
visible object
that we cannot reach
thank you matt c
It is a method that uses
a
scale diagram
of a
triangle
to
indirectly measure
distances to stars
Steps of
triangulation

Here is a tree.
If humans are 1
on this scale,
100 000 000 000 000
000 000 000 000
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 3.
Measure the
angle
from the opposite end of the
baseline

to the tree
Step 1.
Measure and draw a straight
baseline
(ex.120m)
Parallax
is the
apparent shift
of an object against a
stationary background,

Step 4.
Draw a
scale

diagram
with the
baseline
and
angles
Ratio = 10m : 1cm
12 cm
35°
30°
Astronomers
can use the
Earth's orbit
and
parallax

to calculate distance to stars
caused by a
change in the position of the observer
.
Baseline
angle A
angle B
Parallax
comes from the greek word

Which means
"Alteration"
(parallaxis)
=
3.7 cm
3.7 cm x 1000 = 3700cm = 37m
The distance to the tree

is
37 meters.
With these angles, you can use
triangulation
to find the distance
to the star
The longer the
baseline
of the triangle,

The calculations become more
accurate
.

the easier it is to measure the
angles
.
Triangulation
and
parallax

are only accurate
when objects
being measured are within

500 light-years away
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
In conclusion,
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
.
Thank you for watching.
A parsec is a basic unit of length for measuring distances to stars and galaxies, equal to 206,265 times the distance from the earth to the sun, or 3.26 light-years.

The nearest star, Proxima Centauri is about 1.31 parsecs from the Earth.

Parsec
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