Chapter 3 The Moon and Mercury

The Moon

Mercury

Man on the Moon

Obj. #1: Describe the Moon The moon’s equator diameter is 2,160 miles The Moon is approximately 240,000 miles from the Earth The Moon is about ¼ the size of the Earth The noon time temperature of the Moon on the side facing the Sun is 250 degrees

How we know the distance to the moon Scientists used laser ranging to find the distance Apollo astronauts placed reflectors on the moon so the laser would bounce back

Laser Reflectors

The Moons distance from Earth

Dark means cold The part of the Moon that the Sun is not shining on -200 degrees F.

Surface of Moon

Surface of the Moon

What are Maria? When Galileo first looked at the surface of the moon through a telescope, he thought that the dark gray areas were oceans He named them Maria…which is Latin for sea. These were actually ancient lava flows The light area are called highlands

Maria of the Moon are the dark areas The light area is rugged highlands.

A rille is a ditch where molten lava flowed at one time

Moon’s surface has craters ( Greek for bowl) …they were made by meteorites hitting the surface.

Meteroite hits are believed to have caused the change of the Moon’s surface. Lunar dust caused by meteorite hits. This dust is also called regolith which means fine rock layer. Lunar dust covers the Moon’s landscape at an average depth of about 20 meters!

Lunar dust on astronauts shoes

The force of gravity is less on the Moon than it is on the Earth because the Moon has less mass. The force of gravity on the Moon is 1/6 that of the force of gravity on Earth. If you weight 120 pounds on Earth…you would weigh 20 pounds on the Moon!

Obj. #2: Explain what synchronous orbit is Synchronous orbit means that the spin of one body is exactly equal to its revolution around another body. This causes the Moon to have a “near” side that is always visible to Earth and a “far” side, which is never seen.

Synchronous orbit Moon Video

Obj.#3: Describe NASA’s Apollo Program Apollo 11 was the first manned mission to land on the Moon in July of 1969. Neil Armstrong took his famous step and said” That’s one small step for man, one giant leap for mankind”. About 600 million people watched as images were sent to Earth.

Apollo Crew

Armstrong’s famous step

Neil Armstrong plants flag on Moon

Apollo 17 was the last to land on the Moon

Apollo 17 did many surface experiments while on Moon

Obj. #4: Describe 3 theories as to how the Moon came to be 1. Sister theory- The Moon formed as a separate object near the Earth…the same way the Earth was formed. 2. Capture theory- The Moon was formed far from the Earth and was later in time captured by Earth’s gravity.

3. Daughter theory- the Moon came from the Earth itself because of a large impact

Obj. 5: Describe Mercury Found close to the Sun Has an equator diameter of 3,031miles Surface temperature -300F to 872 F In 1974 the Mariner 10 came within 10,000 kilometers of Mercury and took pictures Mercury is about 1/3 the size of Earth

Because of Sun’s glare it is hard for Earth bound people to observe Mercury

Mercury in night sky

Mercury’s surface is cratered like the Moon It takes 88 days for Mercury to orbit the Sun Spin-orbit Resonance- how many times does an object spin on its axis compared to its orbit around the Sun…Mercury has a 3-2 resonance Mercury rotates once every 56 days