The Overall Perspective

Our Greatest TelescopeUnits of Measure

The Cosmic Zoom

Today!

Perspectives On The Universe

The ‘Overall’ Perspective

It helped us discover…

Supernovae, or exploding stars…

Are less bright in the past than we would expect

if gravity ruled the expansion of the universe.

What the universe looked like shortly after the Big Bang13.7 billion years ago

We can watch the planets closely as they change

As in this Hubble Photo of the Martian Ice Caps.

We have even discovered new planets in our solar system!

We need tools with our overalls

One tool is units of measurement

Units ofMeasurement: -Length -Mass -Time

Antoine Lavoisier of the French Academy of Scienceled the search for standards.

The meter was decided to be 1/10,000,000 the distance from the North Pole to the equator. (0.2 mm off)

USEFUL MULTIPLES OF THE METER:

nanometer (nm) = 1 billionth of a metermicrometer ( m) = 1 millionth of a metermillimeter (mm) = 1 thousandth of a metercentimeter (cm) = 1 hundredth of a meterkilometer (km) = 1,000 meters

These prefixes are used for multiplying many units:

Example: The Gigabytes on your hard drive.

Other units are sometimes used to measureAstronomical distances:

Other units are sometimes used to measureAstronomical distances:

The Astronomical Unit – Earth-Sun Distance used within the Solar System

The Light Year is used for distances to stars1 Light Year = nearly 7 trillion miles,The distance light goes in a year.

The parsec is the astronomer’s unit

For measuring large distances

One PARSEC = 3.26 LY

The unit of mass was taken to be the mass ofOne cubic centimeter of pure water.

This is called the GRAM.

You know, like the first, then the SECOND!

The second is 86,400th

Of a mean solar day(Earth is slightly closer to the sun sometimes.Day varies by a few seconds. A mean solar day is the average.)

Did you have a mean solar day Last summer?

The Sumerians (Iraq)Started it all with a god And goddess for each sign Of the zodiac

Thus the watch of each one Was an hour.

The Sumerians also liked the number sixty.Thus 60 minutes,

Tick, tick, tick, tickand 60 seconds.

Another tool is Powers of 10:

Big number--a Gigabyte is 109 , or a one with nine zeros--a billion.

Little number—a femtometer is 10-12 meters or 0.000000000001 meters.

We can use powers of ten to do a…

From the smallest to the largest scale.

As a kid in San Diego I watched

CAPTAIN ZOOM cartoon show!

Smallest is the…

10-33 cm!

100 billion billion times larger is the proton, Or hydrogen nucleus.

100,000 times larger than that Is the typical

atom

10-10 m

A child is about ten billion times larger!

Say 1m

If you got 10 million kids to lay down in a straight lineHead to foot, they could span the earth:10 million meters!

They would LOVE it!

Our solar system—to Pluto is about a million timesThe size of the earth:

1013 m

100 million times broader is our Milky Way galaxy: 1021m

The impressive spiral NGC 1232, which resembles the Milky Way.

The visible universe:

100,000 times broader

At 1026 m

Light can only have come to us from about 13.7 billion light years away.