Why the moon is soundless and other fun facts: A science teacher explains

Is the moon a planet or a star?

The moon is neither a planet nor a star. It is the only natural satellite of our planet Earth.

How old is the moon? Which is older – earth or moon? How is the age determined?

The moon is around 4.51 billion years old, give or take 10 million years. A new analysis of lunar rocks brought to earth by Apollo astronauts suggests that the moon formed 4.51 billion years ago, just 60 million years after the solar system itself took shape. It is younger than the Earth by approximately four billion years. By dating the rocks in Earth’s ever-changing crust, as well as the rocks in its neighbours, such as the moon and visiting meteorites, scientists have calculated that Earth is around 4.54 billion years old.

The age is determined by a process called radioactive dating. By examining the existing elements, scientists can calculate the initial quantity of a radioactive element, and thus how long it took for the elements to decay, allowing them to determine the age of the rock.

How was the moon born?

It was born when a wandering planetismal crashed into the young Earth. Huge amounts of material were thrown into space, eventually coming together to form the moon. This ‘big splash’ theory would explain why the moon’s rocks are very similar to those on the earth.

How far is the moon from earth? How far is the sun?

The moon revolves around the earth in an elliptical orbit. So it gets as close as 363,104 km (225,622 miles) and as far as 406,696 km (252,088 miles). Hence, the average distance between the earth and the moon is around 384,403 km. Similarly, in an elliptical orbit during the course of a year, the earth goes from a distance of 147,095,000 km (91,401,000 mi) from the Sun at its closest point to 152,100,000 km (94,500,000 mi) at its farthest point.

Can you explain phases of the moon?

The moon itself doesn’t emit any light like the sun. What we see, when we see the moon is sunlight reflected off the moon. As the moon circles the earth, we can only see a portion of the lit up side. It is a full moon, when we see 100 per cent of the lit up side. When we can’t see any of the lit up side, it’s called a dark moon or new moon. As the moon orbits or circles the earth, the phase changes. Around once per month, every 29.53 days to be exact, the phases of the moon make a complete cycle.

How many times did man go to the moon? Who was the first? Who was the first Indian?

Twenty-four astronauts, flying on nine different missions, reached an orbit around the moon. Twelve of these astronauts walked on the moon’s surface, and six of those drove Lunar Roving Vehicles on the moon. No country other than USA has put a step on the moon. Neil Armstrong and Buzz Aldrin were the first two astronauts to leave their boot prints on the moon. No Indian has stepped on it as yet.

What are Chandrayaan 1 and 2?

Chandrayaan 1 and 2 are lunar probes sent by India to the moon. Chandrayaan 1 was launched by ISRO in October 2008, and operated until August 2009. It included a Moon Impact prober which landed on moon and gave us evidence of water on it. Chandrayaan 2 had a lander which was supposed to land on the moon and collect more data. The lander did not land softly and hence got disconnected. The orbiter is still in an orbit around the moon.

What if there was no moon?

Here are the top five things we would miss without it:

1. Nights would be much, much darker.
2. Without the moon, a day on earth would only last six to 12 hours. There could be more than a thousand days in one year! That’s because the Earth’s rotation slows down over time, thanks to the gravitational force of the moon and without it, days would go by in a blink.
3. A moonless earth would also change the size of ocean tides – making them about one-third as high as they are now.
4. There will be no solar eclipses without the moon, there would be nothing to block the sun.
5. Without a moon the tilt of our earth’s axis would vary over time. This could create some very wild weather. Without the moon the earth might tilt too far over or hardly tilt at all leading to no seasons or even extreme seasons.

Does the moon have a dark side?

Its far side is the hemisphere of the moon that always faces away from Earth. Both sides of the moon experience two weeks of sunlight followed by two weeks of night; even so, the far side is sometimes called the “dark side of the Moon”, where “dark” is used to mean unseen rather than lacking sunlight.

Does the moon have gravity?

Yes, the moon has gravity but not as strong as the earth. Moon’s gravity is approximately 1/6th of that of Earth. This means, if a person weighs 60 kg (600 newton) on Earth then he/she will weigh just 10 kg (100 newton) on the moon. This is why the lunar astronauts could leap and bound so high in the air.

Is there wind on the moon?

There is no air to breathe or wind on the moon.

Is there water on the moon and who found it?

India’s first lunar mission in 2008 helped confirm the presence of water on the moon. Among its many achievements was the discovery of widespread presence of water molecules in lunar soil. Liquid water cannot persist at the Moon’s surface, and water vapour is decomposed by sunlight, with hydrogen quickly lost to outer space. Also there is no atmosphere on moon to hold the water vapour. However, scientists have conjectured since the 1960s that water ice could survive in cold, permanently shadowed craters at the Moon’s poles.

Short story for kids: The night the moon went missing

Some more cool facts about the moon:

1. The dark side of the moon is a myth. In reality both sides of the moon see the same amount of sunlight, but only one face is ever seen from Earth. This is because it rotates around on its own axis in exactly the same time it takes to orbit the earth, meaning the same side is always facing earth. The side facing away from Earth has only been seen by the human eye from spacecraft.
2. A lunar eclipse happens on a full moon day. But every full moon does not have a lunar eclipse because the orbit of the moon around earth is not parallel to earth’s orbit around the sun.
3. The Sun is 400 times bigger than the moon and coincidently it is 400 times away from Earth as compared to the moon. This is why both the sun and moon appear of equal size for us and the latter can cover the former completely on a total solar eclipse.
4. There is no magnetic field, so explorers could not use compasses on the Moon as we do on the Earth. GPS will not work on moon.
5. The moon is drifting away from the earth. It is moving approximately 3.8 cm away from our planet every year. It is estimated that it will continue to do so for around 50 billion years. By the time that happens, the moon will be taking around 47 days to orbit the Earth instead of the current 27.3 days.
6. The lack of atmosphere means no sound can be heard on the moon, and the sky always appears black.
7. The first spacecraft to reach the Moon was Luna 1 in 1959. This was a Soviet craft, which was launched from the USSR. It passed within 5995 km of the surface of the moon before going into orbit around the sun.
8. The moon is the fifth largest natural satellite in the solar system.
9. During the 1950’s the USA considered detonating a nuclear bomb on the moon. The secret project was during the height of the Cold War between US and then USSR and meant as a show of strength at a time US was lagging behind in the space race.
10. Probably, the moon is one of the heavenly objects on which we find maximum literature in the form of stories, poems, songs etc.

(With inputs from: http://www.space.com, http://www.nasa.gov.in, http://www.isro.guv.in, http://www.esa.int, http://www.ducksters.com, http://www.insidescience.org)

(The writer is Lead, Curriculum – Science & Math at Shiv Nadar School.)