A bright comeback

May 5, 2007 10:05 GMT  ·  By
Meteors streak across the sky against a background of star trails in this long-exposure image.
   Meteors streak across the sky against a background of star trails in this long-exposure image.

On Sunday, a meteor shower will occur when fragments dragged along by Halley's Comet will enter and burn in the night sky.

Called the eta Aquarid meteor shower because their radiant appears to lie in the constellation Aquarius, near one of the constellation's brightest stars, Eta Aquarii, they are not exactly one of the best meteor showers, only the best visible in the southern hemisphere and the moonlight will make all but the brightest meteors impossible to see.

It usually produces around a dozen meteors per hour, but those that are visible may be quite spectacular due to the geometry of the shower.

Last time Halley's Comet passed by Earth was in 1986 and now it lies in the outer solar system. But every time it passes near the Sun on its 76-year orbit, the nucleus of the icy object sheds about 6 meters of material that spreads out along the comet's orbit. Twice a year, the Earth passes near the comet's dusty detritus, producing the eta Aquarids in May and the Orionids in October.

A few hours before dawn, on Sunday, the Earth will enter the comet's space tail and meteors will appear in any part of the sky. This year's spring meteor shower is expected to produce 20 to 60 meteors per hour in the southern hemisphere and only around 5 to 10 per hour in the northern hemisphere.

However, the meteors may be particularly bright because of the speed at which they will be hitting the atmosphere at high speed, about 66 kilometers per hour. This speed is due to the fact that Halley's Comet and the debris it sheds move around the Sun in the opposite direction as the Earth.

The bright meteors known as Earthgazers, will appear to originate from a point near the horizon as seen from the northern hemisphere as the debris will tend to travel sideways through the upper atmosphere.

To see the meteor shower, the best place would be a dark area, preferably outside the area of the city lights and the best way will be to just sit back on a chair or blanket and enjoy the show.