Astronomy 1

Weekly Quiz

In place of a quiz this week, you must be able to identify each inner planet and give several facts for each.

So pay attention!!!!

Inner Planets

The 4 inner planets are small and have rocky surfaces

They are known as the terrestrial planets The are more similar to each other than

they are to the outer planets They all have a core, mantel and crust

Earth 3rd planet from the sun Has an atmosphere

about 100km above the Earth’s surface that has about 20% oxygen and about 78% nitrogen

The atmosphere and temperature range is suitable for water to exist as a liquid

Approximately 70% is covered with water

Earth Has enough gravity

to hold most of the gas molecules (atmosphere)

Geologically active because the internal heat allows for plate tectonics

Mercury Closest planet to the

sun Very small (not much

larger than our moon) Has no moons of its

own Geologically dead Has an iron core Very little is known

about Mercury because it is so close to the sun

Mariner 10 was a space probe that flew by in 1974 -1975, but only got a few pictures

Mercury Very little atmosphere

because the sun heated the gas particles and they escaped into space

Very extreme temperatures – sun side reaches 430°C and at night falls to -170°C (has the greatest temp range of all the planets)

Takes 88 days to complete one revolution

Venus 2nd planet from the sun Venus can often times be

seen easily on Earth – it appears to be a star, but is not because it is reflecting light from the sun

It is the evening star because it can be seen in the west at sunset and the morning star because it can be seen in the east at sunrise

It is known as the Earth’s twin because it is similar is size and composition; however, it is very different in other aspects

Venus Takes about 7.5 Earth

months to revolve around the sun and about 8 months to rotate in its axis So that means that a day

on Venus is longer that a year on Venus!

It rotates opposite of other planets and moons in the solar system It rotates from east to

west This is called retrograde

rotation

Venus Has a very thick

atmosphere – so thick that there is never a sunny day on Venus

This causes the pressure to be 90 times greater than on Earth (it would crush you like a can!)

The clouds are partly sulfuric acid

Has volcanoes, but no other evidence of plate tectonics

Venus Also because of the thick

atmosphere the greenhouse effect is magnified on Venus

The average surface temperature is 460°C

We have had more visits to Venus than any other planet – 19 spacecrafts – one even landed on the surface, but only survived for 23 minutes

Scientists have mapped the surface of Venus and found many volcanoes and strange domes

Mars 4th planet from the sun Called the “Red

Planet” because it is red from the iron in the soil

The atmosphere is mostly carbon dioxide (similar to Earth before life evolved)

Has on about 1% of the pressure Earth has

Has clouds, but only very thin ones

Mars Mars is much colder

than Earth because it is farther from the sun

The south pole of Mars has frozen carbon dioxide or dry ice

Mars has a tilted axis like Earth, therefore it has seasons like Earth

Many spacecrafts have been sent to Mars – a few have landed and traveled on Mars

Mars Those probes are still

on Mars – that is why there have been no manned mission because scientists are unsure of how to safely return back to Earth

Mars has two very small moons Phobos is only 27km

wide (a car could travel across it in 15 minutes)

Deimos is only 15km wide

Both are covered in craters

Mars Temperatures range

from 35°C to -170°C There are strong

winds that blow across the surface of Mars

Last volcanic eruption was around 100 million years ago

Olympus Mons is the largest volcano in the solar system