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| Sunday, 28 November 2004 |
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Junior Observer |  |
| News Business Features Editorial
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Catch a falling star If you have ever seen a falling star, then you have actually seen a meteor which falls to Earth from meteoroids, pieces of stone-like debris that travels in outer space. Meteoroids are small bodies that travel through space. They are smaller than asteroids; most are smaller than a pebble. Meteoroids travel around the Sun in a variety of orbits and at various speeds. The fastest meteoroids move at around 42km per second. Meteoroid orbits Meteoroids orbit around the Sun; different meteoroids travel at different speeds and in different orbits. Some meteoroids orbit together; these are probably comets. Other meteoroids are in sporadic orbits.
Most meteors glow only for a few seconds prior to burning up before hitting the Earth's surface. On most dark nights meteors can be seen. The chance of seeing a meteor without a telescope increases after midnight. People often refer to meteors as falling or shooting stars. The brightest of the meteors are called fireballs. At certain times of the year, more meteors than normal can be seen. When the Earth passes through an orbiting stream of debris from a comet that has broken up, what's known as a meteor shower occurs. These meteor showers take place around the same dates each year. If the meteor does not burn up completely, the remaining portion hits the Earth and is then called a meteorite. Over 100 meteorites hit the Earth each year. Fortunately, most of them are very small. The larger meteorites are believed to have originated in the asteroid belt. Some of the smaller meteorites have been identified as moon rock, while still others have been identified as pieces of Mars. Large meteorites that crashed onto Earth long ago made craters like those found on the Moon. ***** What are meteoroids, meteors and meteorites?
Meteoroid: A piece of debris that is travelling through space towards our planet.Meteor: A brief flash of light that we see at night which is not caused by the material burning with friction from the atmosphere, but instead, from the atoms caused by the object's high speed.Meteorite: A small number of objects that are not entirely destroyed in the upper atmosphere and arrives at the ground. **** The origins of meteor showers Many more meteors can be seen at night during a certain time of the year. The reasons behind this are comets. As a comet orbits near the Sun, it loses materials, such as dust and rocks, which are given out by the tail. These materials cause a continuous trail to form behind the comet as it orbits. When the Earth crosses the path where a tail once was, the particles of materials that they contain are taken up by Earth's atmosphere. These appear in the sky as a shower of meteors. **** Jupiter's coloured spots
Closer inspection has revealed what these spots actually are. They are a rare alignment of three of Jupiter's largest moons, Io, Ganymede and Callisto across the planet's face. The tell-tale signatures of this alignment are the shadows (the three black spots) cast by the moons. However in this picture only two of the moons are visible. Io is the white circle in the centre while Ganymede is the blue circle at upper right. Callisto was located to the right. *** Whirlpool Galaxy
It is one of the original discoveries of Charles Messier. In October 1773 while he was observing a faint comet he found this galaxy. It was named Rosse's Galaxy after Lord Rosse first detected the galaxy's spiral structure in his observations. The NASA Spitzer space telescope image received on November 19 this year shows strange structures in the galaxy bridging the gaps between the dust-rich spiral arms. |
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When debris from one of these enters the Earth's atmosphere, friction
between the debris and atmosphere gases heats it to the point that it
glows and becomes visible to our eyes. This streak of light in the sky is
known as a meteor.
There are three stages to the phenomenon regarding meteors. In the
majority of the cases, an object will only make it to the second stage.
Here are the stages:
In a Hubble space telescope image released recently by NASA, it looked
as if Jupiter has suffered a mild-attack of measles. It seemed to have
five coloured spots, one white, one blue and three black scattered across
the upper half of the planet.
The Whirlpool Galaxy which is also known as M51, Rosse's Galaxy, and
NGC 5194 is a favourite target for amateur and professional astronomers
and is found in the constellation Canes Venatici, 37 million light-years
away.
