SPACE ROCKS
Space rocks are composed of Asteroid, Comet, Meteoroids, Meteors and Meteorites that we see flying around the Solar System or crashing down to Earth. Almost all of these are remains of the creation of the Solar System. They mostly came from the Asteroid belt, the Kuiper Belt, and the Oort cloud.
Where do space rocks come from?
Fig.1. The Solar System, showing the origin of space rocks
Before we tackle space rocks first we should learn where they come from. There are three mostly known regions where space rocks come from:
They mostly came from the Asteroid belt, the Kuiper Belt, and the Oort cloud.
Asteroid Belt
The Asteroid belt is found between Mars and Jupiter. The objects that can be found in the asteroid belt are made of rock and metal. It contains billions of asteroids. Some are large, but most range in size down to pebbles. There may be a lot of objects in the asteroid belt, but they are far away from each other that allows spacecraft to pass through this region without hitting anything.
Kuiper Belt
Kuiper belt is a region that lies beyond the Neptune. It has a disc-shaped filled with icy objects. But the astronomers described it as being more torus-shaped than a belt. Most of the short-period comets have been traced coming from here, which have an orbital period of 200 years or less. It can contain hundreds of thousands of icy bodies that range in size from small chunks of ice to more than 100 kilometers. There may be more than a trillion comet nuclei in the Kuiper Belt’s main body.
Oort Cloud
Figure 2. Oort Cloud
According to the Dutch astronomer Jan Oort, the nuclei of long-period comets come from a giant spherical cloud surrounding the solar system, called Oort cloud. It is theorized as a shell of icy objects that lie beyond Kuiper Belt. It is composed of methane, ice and ammonia and its full of asteroid and comets. Oort cloud has 2 distinct parts: an inner disc-shaped known as Hills Cloud, and an outer in the spherical form. The solar system’s cosmological boundary is defined by the outer limit of Oort cloud and the Sun’s gravitational dominance ends with Oort cloud.
What are the different type of space rocks?
As we said earlier, space rocks are composed of Asteroids, Comets, Meteoroids, Meteors and Meteorites. For us to better understand the different kinds of space rocks, please to the illustration below.
Figure 3. Space Rocks
Asteroids
Asteroids are the biggest type space rocks. As mentioned above, they are located at the Asteroid Belt. They are made of rock and iron, like Earth but they are smaller. Did you know that if all asteroids are put together, it would be still smaller that our Moon! (This is according to Space.com)
An example of an Asteroid is Ceres. It was the first asteroid to be discovered in the Asteroid belt! Also, due to its planet like figure, Ceres is also considered as a dwarf planet!
Fig.4 Ceres: Not just not an asteroid also a (dwarf) planet!
Comets
Another example of space rocks are the comets. It is made of ice and rock originating from the outer solar system, which is the Oort Cloud or the Kuiper Belt. Like the planets, they orbit around the Sun, but with more elliptical orbit, which their travel is farther.
A prominent example of a comet is the Halley’s Comet. It was discovered by Edmund Halley in 1705. Halley ’s Comet is known to be a very magnificent comet when seen on Earth. The next time we are going to see this comet is on July 2061 (as calculated by scientists). So be ready!
The Magnificent Halley's Comet
Meteor vs. Meteorite vs. Meteoroid
Meteoroid
It is a small rocky or metallic object traveling through space. Meteoroids are significantly smaller than asteroids, and range in size from small grains to 1 meter-wide objects. Most are fragments originated from comets or asteroids, while others are the collision of impact debris ejected from bodies such as the Moon or Mars.
Fig.5.Meteoroid
Meteor
Meteors typically occur in the mesosphere at altitudes between 76 km to 100 km (46-62 miles). The root word ‘‘meteor’’ comes from the Greek word meteoros, meaning “suspended in the air”. Millions of meteors occur in the Earth’s atmosphere daily.
Meteors are meteoroids that have entered the Earth’s atmosphere and starts burning up. The same reason why its appearance looks like a streak of light and usually referred to as a “falling star”.
Fig.6.Meteor
Meteorite
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If a meteor doesn’t entirely burn up, a piece of space rock that land on Earth is called a meteorite. All meteorites were the product of larger objects and have fallen to Earth from space.
Fig 7. Hoba Meteorite, the largest in on Earth
Prominent Meteor Showers in the Philippines
Meteors can occur anytime of the year, but some meteor showers usually appear around the same time every year. There are many meteor showers that occur around the world. Here are some that usually appear and can be seen at the Philippines:
Quadrantids
The first meteor shower of the year. Usually occurring between the last week of December to January 12. It peaks around January 3 and 4. Best seen from the Northern Hemisphere. The radiant point lies in the constellation Bootes.
Lyrids
Lyrids occur between April 16 to April 26. It peaks around April 21-22. The radiant point of the Lyrids lies in the constellation Lyra.
Eta Aquarids
Eta Aquarids occurs between late April and mid-May, peaking around May 5-6. Best seen from the Southern Hemisphere. Meteoroids in the Eta Aquarids are remnants from Halley’s Comet. The radiant for this shower lies in the constellation Aquarius.
Perseids
Perseids occurs in mid-August and reaching the peak activity around August 11-13. Its radiant point lies in the constellation Perseus and it is associated with the comet Swift-Tuttle.
Orionids
It occurs every October and reaching the peaks around October 21-22. The name of this shower comes from the constellation Orion. It is also associated with the debris from Halley ’s Comet.
Leonids
It occurs during the month of November and usually reaching its peaks around November 17-18. It is associated with the comet Tempel-Tuttle and is named after the constellation, Leo.
Geminids
Geminids occurs in early December. It peaks around December 13-14. The Geminids owes their name to the constellation Gemini and is the only major meteor shower not associated with a comet, but with an asteroid.
