Foundations of Astronomy

Science and Religion in Schools Project - Unit 4aThe Scientific Account of the Beginning

The Sun

Ball of super-hot gas Core temperature 16 million

degrees ºC Roughly 4.5 billion years old Will last another 4.5 billion

years A very typical star

The Solar System

In this image, the planets are in the correct order The relative sizes of the planets is about right, but the

distances are not The Sun is the arc on the far left!

Mercury 0.4 times Earth’s diameter No atmosphere worth mentioning Surface temperature 1700C on

average Mercury rotates two times for

every three orbits round the Sun Takes 88 days to orbit the Sun Distance from the Sun is about

0.4 times that of Earth

Venus Clouds are too thick to see the

surface Venus is bright as these clouds

reflect a lot of the sun’s light Surface of Venus is hot (4600C) Atmospheric pressure is about 90

times that on Earth Surface features only ‘seen’ by

radar

Guess where?

Meteorites

Lumps of rock from space that generally burn up in the atmosphere

Some large ones make it to the surface and can cause damage

The Moon

Orbits the Earth No atmosphere Some water, as ice Craters due to being hit

by meteorites Probably made when a

giant meteor hit the Earth and blasted part of the crust into space

Phases of the Moon

Moon keeps the same face to the Earth

Time it takes to turn on its axis, same as the time taken to orbit Earth

Phases dependent on how much of the Moon visible from Earth is lit by the Sun

Mars

Atmosphere is carbon dioxide Atmospheric pressure is

0.75% of Earth’s Smaller than Earth, but about

the same size of land area Being well explored by

unmanned probes

Martian Surface

Olympus Mons

Olympus Mons is the large volcano in the top left

The pale features are clouds drifting over the region

Jupiter

Largest planet in the solar system

Composed entirely of gas Black dot is the shadow of

Europa Large red dot is a hurricane

- bigger than Earth 11 times the diameter of

Earth and a thousand times more massive

Saturn

Beautiful gas giant Nearly as big as Jupiter Ring system can clearly be

seen from Earth with even a small telescope

Saturn’s rings

Complex structure of rings Large gap is the Cassini

division

The F ring contains shepherd moons

The Moons lap each other every 25 days

Can cause the rings to be ‘braided’

Uranus True colour image from Voyager 2

makes Uranus seem bland Infra-red image from the Hubble

Space telescope shows more activity and the thin ring system

Hubble image shows cloud structure

Also that Uranus rotates on it side - so it ‘rolls’ around the Sun, unlike the other plants

Neptune Final gas giant Similar in size to Uranus Great dark spot was thought to be

a storm system, but could be a ‘hole’ like the hole in Earth’s ozone layer

High altitude ‘wispy’ clouds can also be seen

Pluto Pluto’s orbit crosses that of Neptune Also highly angled with respect to the other planets Pluto’s moon Charon was discovered in 1978

New planet? Discovered on 14 November 2003 Far beyond Pluto Orbit yet to be worked out Status as a planet to be determined

(is it big enough?) Provisionally called Sedna, the Inuit

goddess of the sea, who was believed to live in the cold depths of the Arctic Ocean

The Milky Way

Andromeda Galaxy Nearest galaxy to the Milky Way Still about 2 million light years away In about 3 billion years, Andromeda

will collide with our galaxy Can be seen with the naked eye on

a dark night

Deep Field One of the most important

pictures ever taken Hubble space telescope Try to count the number of

galaxies! This patch of sky could easily

be covered by the end of your finger at arm’s length