Rita's Science Blog: March 2011

How was the Moon formed?

Fission Hypothesis

There are those who believed the Earth spun so fast that a portion of its crust broke off to form the Moon. This theory is believable because if the Moon came from the Earth's crust, it explains how the Moon has a low composition of iron. Earth has a large iron core but has a lower concentration of iron in its crust.
However, the hypothesis isn't very believable in total angular momentum and energy analyses in connection to the Moon’s formation.

Capture Hypothesis

Others once believed the Moon came from another part of the Universe with little iron, strayed near the Earth’s gravitational field, and was drawn into orbit. However, there are 3 main reasons why this hypothesis may be incorrect.
Firstly, the isotope composition of Moon rocks is very similar to that of rocks from our planet. Second is the necessity for a very small encounter velocity, because in order for the Moon to be drawn into the Earth's gravitational field in the first place, then the Moon must have approached at a very slow velocity or it would have collied with the Earth. And third, is the absence of a very thick atmosphere that should have been present to provide a 'gas drag' that would have helped in the capture process.

Co-Formation Hypothesis

Others believed that the Eart and Moon were formed at the same time and in the same region in the solar nebula, drawing materials to each other from the dust around them. Even though this theory explains the proximity in the distance between the Earth and the Moon, and how the Moon is believed to be roughly as old as the Earth. However, it doesn't explain why the Moon has less iron than the Earth.

Giant Impact Hypothesis

However, the hypothesis that most are accepted by most people nowadays is the Giant Imapct Hypothesis. In this hypothesis, the Moon is believed to have been originally a part of the Earth’s crust, but at some point of the Earth's existence, another body similar to the size of Mars collided with the Earth, extracting a chuck of the Earth's crust.

This is considered to be believable, because if the Moon came from the Earth's crust, it would explain the lack of iron in the Moon. Furthermore, computer simulations also show how this theory is consistent with angular momentum measurements.
http://www.universetoday.com/47996/how-was-the-moon-formed/

How old is the Moon?
4 and a half billion years old (similar to the Earth)
http://lunarscience.nasa.gov/kids/age

Why does the Moon only show one side to us all of the time?
The time taken for one complete rotation on its axis (29.5 days) and the time taken for it to revolve around the Earth is the same which isn't a coincidence because the Moon used to rotate around it's axis much faster but over millions of years this has slowed down due to the effect of Earth's gravity. This movement is called Synchronus rotation.
http://library.thinkquest.org/29033/begin/earthsunmoon.htm
http://starryskies.com/The_sky/events/lunar-2003/eclipse9.html
http://www.wisegeek.com/why-does-the-same-side-of-the-moon-always-face-the-earth.htm

The Moon is slowly drifting away from us, by how much per year?
1.5 inches (3.74 centimeters) every year.
http://www.space.com/2759-earth-moon-planet.html

Explain what will eventually happen to it
It would be come a planet on its own
Definition of a planet: any round planet orbiting around the sun and has it's own centre of gravity (currently the Moon's barycentre is in the Earth)
This wooul not occur for billions of years
http://www.space.com/2759-earth-moon-planet.html

How much larger is the Sun than the Moon?
The Sun is 400 times larger than the Moon, with a diameter of 865,000 miles whereas the Moon's diameter is only 2,160 miles.
http://www.bigsiteofamazingfacts.com/which-is-bigger-the-sun-or-the-moon

How far away is the Moon?
238855 miles ( 384400 kilometers) away from Earth (about the width of 30 Earths)
http://coolcosmos.ipac.caltech.edu/cosmic_kids/AskKids/moondist.shtml

What was significant about the 19th March 2011 (regarding the Moon)?
There is the Supermoon which means that the Moon has been the closest to the Earth than it's ever been in 18 years which is 356,577 kilometers (221,567 miles).
http://www.24x7newsportal.com/2011/03/supermoon-19-march-2011-moon-closest-to.html

Why is there no atmosphere on the Moon?
The Moon has too small a mass to maintain a gravitational pull required to prevent gases from quickly escaping its surface. Unlike Earth, it is also geologically and biologically dead which means that it cannot replace the gases that leave its surface.
http://www.astro.uu.nl/~strous/AA/en/antwoorden/maan.html#v99

Why is the gravity on the Moon 1/6th than of Earth?
Because the mass of the Moon is 1/80th of the Earth, and since mass determines the strength of the object's gravitational pull, the grativity on the Moon is hence only a sixth of the Earth's, and if we stand on the Moon we would feel only 17% of Earth's gravity (the Moon pulls you down less strongly hence the ground pushes up with less force).
http://www.astro.uu.nl/~strous/AA/en/antwoorden/zwaartekracht.html#v82
http://www.universetoday.com/19710/gravity-on-the-moon/
http://www.newton.dep.anl.gov/askasci/gen01/gen01564.htm
http://www.moonconnection.com/moon_gravity.phtml

What natural phenomenon does this ratio help to observe?
The weight of any object changes when on Earth and when on the moon (objects weigh less on the Moon), as Weight = Mass x Gravity, and since the gravity of the Moon is 1/6th of the Earth's, we can calculate the change in weight of any object. We would also be able to jump much higher than on Earth due to the decrease in weight,

Insert a video (and source) of the answer to the question above

http://www.youtube.com/watch?v=isVO9AAAhxM&feature=related

How many people have stepped on the Moon? Who was the last?
12 people so far have walked on the Moon. The last person who walked on the Moon was Harrison Schmitt.
http://en.wikipedia.org/wiki/List_of_Apollo_astronauts#Apollo_astronauts_who_walked_on_the_Moon

Why does the Moon orbit the Earth?
The Moon is attracted to the Earth's gravitational pull due to the fact that the Earth has more mass and has a greater gravitational field, in which this tug on the Moon is called the centripetal force and is balanced by the centrifugal force which in turn pulls on the Earth and keeps the Moon moving and in orbit around the Earth. Moreover, due to the Earth's mass, it distorts spacetime in the vicinity of the Moon (derived from Einstein's Theory of General Relativity). This distortion or curvature influences the motion of the Moon's orbit as well.
http://curious.astro.cornell.edu/question.php?number=192

How many days does it take to orbit?
27.3 days (a sidereal month).
http://en.wikipedia.org/wiki/Orbit_of_the_Moon

What effect does the Moon have on the Earth?
Firstly, the Moon's position around the earth allows it to reflect the sun's light and hence the Moon shines during the night time. The moon's orbit around the earth lasts about a month giving us different levels of this light. The new moon provides limited amount of light, whereas the full moon provides us with the brightest light at night. The second effect comes from the Moon's gravitational pull on the Earth. As the earth rotates, the Moon's pull causes the oceans to experience high tides. At any given time, there are two high tides on earth.

Insert a video (and source) of the answer to the question above

http://www.youtube.com/watch?v=rRPtNAA-9UE&feature=related

Other planets have moons, find images if those moons
Deimos (Mars):