viernes, 1 de marzo de 2013

We could have evolved without the Moon
Our world would certainly be quite different if it had no large satellite. But apparently it would not be so radically different that its absence would necessarily prevent humans from ever seeing the light of day.
Another question is what would happen if the Moon were to suddenly decide to say goodbye. Would we survive that?
“Yes we would. Nothing too severe would happen because the Moon could never vanish instantaneously. It would slowly get further away and eventually leave us. But there’s nothing indicating that we’ll lose the Moon, so this is purely hypothetical,”Aksnes assures us.
The night sky would be less interesting, but we could survive without the Moon, according to Aksnes. (Photo: Colourbox)
The Moon actually is in the process of leaving us, at a rate of nearly four centimetres a year. Neither the oceanic tides nor the length of the day are particularly crucial to our survival, so the most important aspect of this separation is the way the changes in the Earth’s tilt would impact us.
“I would expect the Earth to still be habitable, even when considering large changes in the axis. The Earth can be compared to a spinning top. The force of its rotation makes it relatively stable. Despite losing the stabilizing Moon it would take a long time before the tilt of Earth’s axis changed much,” Aksnes points out.
“If for instance you look at the life expectancy of a civilization as a few thousand years, the changes would be so slowly paced that we could have time to adapt.”
If you are still nervous about what will happen eventually as the Moon orbits further and further away, you might find solace in the following: By the time any serious consequences could occur, the Sun will have become a red giant and will have consumed both the Earth and the Moon.
Earth vs Moon
The moon has always been a source of wonder man started walking the Earth. Visible mostly during night time, the moon’s light is more subdued than the sun, and it changes shape depending on the time of the month. The moon has also blocked the sun in the past, a very rare phenomenon known as a solar eclipse. There are many legends and superstitions connected with the moon. For example, it is said that during the full moon, werewolves roam freely and witches are able to perform magic. In reality, however, all the moon really does is affect the tides because of its gravitational pull on the Earth.
While most people already know the differences between the Earth and the moon, there are some who are still confused when it comes to differentiating one from the other. The first major difference between the two heavenly bodies is that the Earth is a planet, while the moon is merely a satellite orbiting Earth. Planets usually have satellites orbiting them. It just so happens that our planet has only one satellite, that’s why we simply call it the moon. Other planets, such as Saturn and Jupiter, have a lot of moons. Each of their moons has a specific Greek name for easy identification by astronomers. Astronomers are usually able to tell apart a planet from a moon based on the size of the heavenly body. No moon can equal or surpass the size of a planet. All satellites are smaller in diameter when compared to planets, and they also have different atmosphere and surface conditions.
The second major difference is due to the moon’s smaller size. When put side by side with the our planet, the moon only has one-fourth of the Earth’s total diameter, and much less mass. The moon has a weak atmosphere, unlike the Earth which has a multi-layer atmosphere. Because of its almost nonexistent atmosphere, the moon is incapable of supporting life. Astronauts who walked on the moon had to wear vacuum-sealed suits with oxygen supply, otherwise they would simply die if they wore normal Earth clothing.
The third major difference is that the moon’s gravitational pull is only one-sixth to that of the Earth’s. This means that a person can jump six times higher on the moon than on the Earth. However, the moon is still able to exert some gravitational pull on the Earth, which is demonstrated by the occurrence of tides.
The fourth major difference is that there is neither oxygen nor water on the surface of the moon. Earth has a lot of water on its surface, comprising more or less seventy percent of its crust. Earth also has a lot of oxygen, thanks to its multi-layer atmosphere. On the other hand, the moon’s weak atmosphere disables the formation of oxygen and water on its surface, making the moon a barren, lifeless world.

miércoles, 27 de febrero de 2013

The Earth is larger than the Moon. The Moon's smaller mass means that the gravity on the Moon is only about 1/6 of the gravity at the Earth's surface.

  • The Earth is 12,756 km in diameter
  • The Moon is 3,476 km in diameter

If the Earth was the size of a basketball, the Moon would be the size of a tennis ball in comparison. However, of all the moons in the solar system, our moon is largest in proportion to the planet it orbits. All other moons, even the ones larger than our moon, are much smaller when compared in proportion to the planets they orbit.
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Figure 2: The positions of earth at the different seasons. Counterclockwise from lower left: summer, fall, winter, spring (northern hemisphere).
The earth’s orbit is called the ecliptic. The plane which contains the ecliptic is the reference plane for the positions of most solar system bodies. Viewed from earth, the ecliptic is the apparent motion of the sun among the stars.
The earth’s equator is a circle going around the earth which is on a plane that is perpendicular to the earth’s axis
The Earth, Sun, and Moon
The Earth
Earth, which is our base from which we look into space, is constantly moving. Understanding this movement is one of the most useful and important things in astronomy.
The earth orbits the sun in an elliptical orbit and the moon orbits the earth with the same kind of orbit. Looking down from the north pole, the earth spins in a counterclockwise direction on an imaginary line called its axis once every day. This accounts for the fact that the sun rises in the east and sets in the west. The earth’s axis is tilted with respect to the plane of its orbit at an angle of about 23.4 degrees. If we position ourselves high above the north pole, we would see that the earth orbits the sun in a counterclockwise motion, coming to the same position among the stars every 365.26 earth days. We would also see that the moon also orbits the earth in a counterclockwise motion.