What is Astronomy?

A Study Of:

Astronomy What are some reasons for people, as a whole, to study Astronomy?

What are some reasons for you, personally, to study Astronomy?

What is Astronomy?

A Search For:

Astronomical ScaleThe Universe and the

things in it are bigger than we can imagine. To help, we use:

Models--Representations of real objects or events

Certain aspects of a model HAVE to be incorrect

What are some models that are used in Astronomy?

Scientific Notation Because the universe is so

big, it is easier to use scientific notation as an abbreviated way to write down numbers.

This will also make very small numbers with a lot of decimal places much easier.

Scientific Notation For example:

93,000,000

1. Write down the “non-zero” numbers, and put a decimal point after the first number.

9.3

Scientific Notation For example:

93,000,000

9.3

Then count the number of zero’s or places that follow the new decimal and write them in an exponent like this:

1 234 567

x 107

Scientific Notation For a small number like:

0.00000234

1. Write down the “non-zero” numbers, and put a decimal point after the first number.

2.34

Scientific Notation For a small number like:

0.00000234

2.34

Then count the number of zero’s or places that follow the new decimal and write them in a negative exponent like this:

123456

x 10-6

Write the following in Scientific Notation:

3,400 0.0920 401,000 0.000000045 60,000,000,000 150,000,000,000

Convert the following from Scientific

Notation: 7.3 x 105

3.001 x 103

6.11 x 10-6

4.9 x 1010

1.7 x 10-4

2.4 x 108

Astronomical Unit

The average distance from Earth to the Sun miles m

AU’s are used for distances like those

Image Link

Light-year

The distance light travels in one year. **A Distance** Sp. of light = miles/sec

1 ly = km AU

How many miles in one ly?

Light-year

The nearest star, Proxima Centauri, is ___ ly from Earth.

If the sun were a golf ball in NYC, the nearest star would be in _______.

Light-year

The sun is 8 light-minutes from Earth. (93 million miles)

Light years are used for larger distances like those between stars.

Looking at the Stars

Size of the “dots” in the sky only represents the brightness of the stars,

not the size or distance.

Brighter stars make larger dots on photographs

Our sun is a faint star and would probably not show up in Fig. 1-10

Looking at the Stars

Only a century ago, scientists thought the galaxy was the entire universe, of which our sun is in the outer part.

Having billions of galaxies makes it hard to keep a proper sense of scale.

Alpha Centauri

Central Bulge of Milky Way

Billions of GalaxiesBillions of StarsBillions of Planets?

Life only on Earth?!