Meteors

Meteors are streaks of light (like lightning) flying through space. They usually last only a few seconds and can be seen in the night sky. These are what people sometimes call "shooting stars" or "falling stars", eventhough they aren't stars at all.

Meteors are caused by small pieces of rock, dust or metal entering the atmosphere from space at a very high speeds. They are called meteoroids (like asteroids) when they are still in outer space. They travel at speeds of tens of km/s when they reach Earth's atmosphere. The high pressure that meteoroids experience when they break through Earth's atmosphere shatters them. This transfers energy to atoms & molecules on Earth. They then release energy by glowing, which produces the trail of light we see as meteors.

Most meteoroids are very small. Their sizes range from a grain of sand to pea-sized stones. Almost all on them disappear before they can reach the ground. A larger meteoroid can actually survive to hit the ground, but this happens very rarely. They then create a meteor crater if the explosion of colliding with the ground is big. This explosion usually vaporizes any solid parts left of the meteor after burning through the atmosphere. But sometimes, solid pieces of meteoroid survive & can be found in and around the crater. These little pieces are called meteorites.

Meteors are different from comets. You'll see why in the next post.

Extremely bright meteors are called fireballs. Some fireballs can even be seen at daytime. (O.O) You can see meteors above any planet that has an atmosphere (eg. on Mars). The picture on the left shows the Leonid Meteor Shower in November 1998. It also include a fireball. ^.^

A meteor shower happens when there are many meteors in one night. Sometimes even more than 100 meteors per hour. This happens when Earth crosses the orbit of a comet. Dust and other particles that have been left behind is what we see as meteors.

Asteroids

I think writing about asteroids would sound fun right now. So I'm writing this...
Asteroids are small bodies in our solar-system, that are said to be the leftovers from the formation 4.6 billion years ago. They are rocky objects & have a wide variety of shapes. Some are round, others rather irregular. Their sizes also vary (up to a few hundreds of kilometers across, but most are much smaller).
More than 100,000 asteroids in our solar-system lie in the Asteroid Belt, which is located between Mars & Jupiter. There are many asteroids there. If there weren't any asteroids, the space between these two planets would be greater than the space between any other planets next to each other.
Scientists claim that asteroids (especially the ones in the Asteroid Belt) are the remains of a planet in our solar-system that's already gone now. Thousands of the biggest asteroids have names today.
Eventhough the chances are very small that an asteroid will collide with Earth, they still come close to Earth, like Hermes (came as close as to 777,000 km from the Earth). Anything might happen at any time!

The Solar-System

Here, I decided not to write as much as my previous entries. I will just write about the solar-system as a whole.
The Solar-System as a whole, consists of eight planets and their 172 known moons, asteroids, comets, dust & gas.. And of course, also the dwarf planets & their moons, and other flying bodies.... xp
Most of the bodies of our solar-system travel around the Sun along nearly circular paths, also known as orbits. They all travel in an anti-clockwise direction when you see the whole solar-system from above.
This formation of this solar-system began billions of years ago (that's a VERY long time if you think about it!).. It began when dust & gases came together to form the Sun & other bodies in our solar-system.

Makemake

Makemake is the fourth official dwarf planet here. It was officially called a dwarf planet in July 2005, just about two months before Haumea. It is also a large KBO. Like other planets that orbit our solar-system from the edge, it is also icy & cold (temperature of about -240°C). Because it is vary far away, it also needs a very long time to orbit the Sun once (nearly 310 years!).. O.O And clearly therefore, it is also usually farther from the Sun than Pluto.

It is smaller than Pluto & Eris and its diameter is only between 1,300 km to 1,900 km. That is about three quarters of the size of Pluto. But astronomers haven't discovered any moons for Makemake yet. This is a bit odd, because other large KBO objects have at least one moon. Makemake may be covered with ice, that is made of methane & maybe ethane too.

The surface of this planet is bright, something you would expect from a surface of ice.. But it is also kind of red in colour, which you wouldn't expect....

It may also have an atmosphere (some of the time). When this dwarf planet come closer to the Sun in its orbit, it warms up. This may cause the methane & ethane gases then to form an atmosphere. When it gets further from the Sun, Makemake may cool down. Then the gases would fall onto its surface as 'snow'.. So, the atmosphere's gone again! BUT again, this is only theory. Scientists aren't sure if this happens. This might also happen to Pluto.. Who knows, right?

Like Haumea, it is also named after a god, but not a Hawaiian one. This time, it's a god from the mythology of the Rapa Nui people of the Easter Island (the place with the 'world wonder' statues). He is the god of fertility & the creator of humans in the mythology. As you know, July 2005 is also not long after Easter 2005, therefore, astronomers nicknamed it "Easterbunny" :-0 This is funny ^.^ So, when they had to choose an official name for this planet, they decided to name it after a character from the mythology of Easter Island.

Makemake, with Pluto & Eris (not Ceres!), is also called a "plutoid". These are dwarf planets, like Pluto, that orbit the Sun from beyond the planet of Neptune. Ceres orbits the Sun before Jupiter.

Haumea

Haumea is the fifth official dwarf planet in our solar-system. The four before it are Pluto, Eris, Ceres & Makemake. It was classified as a dwarf planet in September 2008. It is a large Kuiper Belt Object (KBO). It was labelled 2003 EL61.
Haumea is also very cold & icy (the temperature is about -241°C). It orbits the Sun from the far edge of the solar-system too & it takes 285 Earth years to orbit it just once. Usually it is farther from the Sun than Pluto.

Haumea is smaller than Pluto & Eris and it has an odd shape... This odd shape is because the planet is spinning so fast that it is pulled into an ellipsoid (a 3D ellipse). Haumea is 1,960 km across measured from the farthest ends & only about half of that (996 km) from the nearest points across. Therefore also, the days on Haumea are very short. They are less than 4 hours on Earth! It is also dense, which means, most of it is probably just made up of rocks.
Most of the other KBOs probably has more ice on them than Haumea. It has two known moons (like Mars), which were both discovered in 2005. They are called Hi'iaka & Namaka.

Astronomers think that Haumea crashed with another object a long time ago. That would be another reason for the weird shape & also why it spins so fast. The collision might also have caused much ice on Haumea to fly away, so there is less ice now. Its moons may be just some leftovers from the crash.
There are two different groups that might get the credit for discovering this planet. One groups is led by Mike Brown of the California Institute of Technology. The other group is led by José Luis Ortiz Moreno from the Sierra Nevada Observatory in Spain. Haumea was discovered between March 2003 & July 2005. Before it was called Haumea, while it was still coded, it was given the nickname "Santa" by Brown's group because they discovered it around Christmas 2004.
In the Hawaiian mythology, Haumea is the goddess of fertility & childbirth. She had three children named Hi'iaka (Hawaiian sea goddess), Namaka (goddess of hula dancers) & Pele (Hawaiian goddess of volcano & fire). This is where the two names of its moons come from.

Eris

Eris is the largest know dwarf planet in our solar-system. It is also one of the first 3 objects categorized as a 'dwarf planet', with Pluto & Ceres. Eris was first recognized in January 2005. Some astronomers called Eris our "tenth planet" when it was first discovered (in 2003 by Michael Brown, Chad Trujillo, and David Rabinowitz). But after discussions, they decided to have a new category for objects like Eris. It is similar to Pluto, because it is a large sphere of ice & rock.

The temporary name of Eris was "2003 UB(313)", because 2003 was the year they first discovered Eris, and then nicknamed "Xena" before it was called Eris. Eris has a moon called Dysnomia. Before that, it also had a nickname -> "Gabrielle".

The diameter of Eris is about 2,500 km (1,553 miles - a little bit bigger than Pluto), but we can't be sure of it's exact size, because it is too far to see clearly, even with the world's best telescopes!

Here is a picture, so you can see the position of Eris:

Eris' orbit is not like the orbit of other planets or dwarf planets, because its orbit is like a flattened circle. Eris takes 557 years to fully orbit the Sun just once! The surface temperature on Eris is about -250°C..! Cold, isn't it?

Ceres

Ceres is the largest asteroid in the main Asteroid Belt. It was classified as a 'dwarf planet' in 2006, alound with Pluto & Eris. Ceres was discoved by the Italian astronomer (and monk) Guiseppe Piazzi.




The diameter of Ceres is about 975 km (605 miles - about the size in the picture). It is much bigger than the other objects & bodies of the main asteroid belt & contains about a third of the belt's total mass. It orbits the Sun once every 4.6 Earth years. As you already know, its orbit lies between Mars & Jupiter, because it is part of the asteroid belt. A day on Ceres is about 9 hours on Earth, because the asteroid turns on its axis once every 9 hours.