meteor

A meteor is typically a lump of rock or metal falling from space into the upper atmosphere. If it makes it all the way to the ground it becomes known as a meteorite. Thousands of them crash into our skies each year, but most are not seen by people on the ground as they fall over uninhabited parts of the planet or are too small to show up. They also tend to break up rather quickly, so you are lucky to spot them. A person's best chance comes during a predictable meteor shower, such as the Leonids.

There was one night that I was fortunate enough to see a much larger and longer lived meteor from a French beach, overlooking the Atlantic Ocean. The sight was so special to me that I took in a lot of detail and am now able to describe to you those few seconds of it's flight.

The meteor appeared to my left, in my deep peripheral vision. At first it was just a yellow light that travelled almost horizontally. It grew to an incredibly bright white in a second and I turned to look at it, assuming it was a fighter jet flying low over the coast. As I focused on the object it began to dim slightly and changed to a greener colour. Pieces of it broke off and created a trail of smaller meteors in its wake. These sparkled and turned orange as they dimmed.

The main chunk started to dip towards the sea after maybe three seconds of my observation and the whole shower darkened to a red as it disappeared into the haze of the horizon. It lasted a total of around six seconds, but the memory will last forever.

Looking back on this sighting I have thought about how fast and how far away the meteor must have been. It's not unreasonable to assume that it was travelling at around 50km per second on entry, so even allowing for slowing it must have travelled around 250km by the time it completely broke up. I estimate the length of the trail of visible debris was around 100km and that the whole thing occurred several hundred km away from me.

Meteors or shooting stars are caused by dust particles from comets burning up in the atmosphere at a height of about 100km (60 miles). There are sporadic meteors falling all the time, but at set times in the year there are meteor events when the Earth's orbit takes it through the tail of a comet. The meteors appear in a set area of the sky and seem to originate from a single point. Ths point is known as the radiant, and the meteor shower is normally named after the constellation that the radiant appears to be in.

This is a list of the most common meteor showers that are easily visable to the naked eye, and when to look out for them.

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JANUARY
The Quadrantids

• Appear: Northern Hemisphere only
• Radiant: Bootes (Near the handle of the Big Dipper/Ursa Major
• Occur: 1st week of January
• Peak: 3rd-4th January
• Maximum Activity: 100 meteors/hour at peak
• Description: Faint meteors, best viewed after midnight when the radiant is high in the sky.

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APRIL
The Lyrids

• Appear: Both latitudes, but best seen in the Northern Hemisphere
• Radiant: Lyra (Vega, one of the stars in Lyra, is the fifth brightest star in the sky, not too hard to spot.)
• Occur: 18th-23rd April
• Peak: 21st April
• Maximum Actvity: 10 meteors/hour at peak
• Description: Fast and bright with spectacular trails.

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MAY
The Eta Aquarids

• Appear: Both latitudes, but best seen in the Southern Hemisphere.
• Radiant: Aquarius (Caused by dust from Halley's Comet.)
• Occur: Late April into late May
• Peak: 5th May, but is good throughout the first week.
• Maximum Activity: 35 meteors/hour at peak
• Description: Bright and fast moving.

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AUGUST
The Perseids

• Appear: Northern Hemisphere only
• Radiant: Perseus
• Occur: Throughout late July and August
• Peak: 12th August
• Maximum Activity: 75+ meteors/hour at peak
• Description: The best meteor shower of the year. Meteors often flare, are bright and fast moving and often leave trails.

See also: Perseid Meteor Shower

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OCTOBER
The Orionids

• Appear: Both latitudes
• Radiant: Orion (Again, caused by dust from Halley's comet.)
• Occur: 18th-23rd October
• Peak: 21st October
• Maximum Activity: 25 meteors/hour at peak
• Description: Fast moving, but faint. Best viewed after midnight when the radiant is high in the sky.

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NOVEMBER
The Taurids

• Appear: Both latitudes
• Radiant: Taurus (near the Seven Sisters/Pleiades)
• Occur: Throughout late October and November
• Peak: 5th November, but is good throughout the first week.
• Maximum Activity: 10 meteors/hour at peak
• Description: Bright and slow moving.

The Leonids

• Appear: Both latitudes
• Radiant: Leo (Caused by Tempel-Tuttle comet with a peak time of activity every 33 years. The last peak was in 1999.)
• Occur: 16th-18th November
• Peak: 17th November
• Maximum Activity: 10 meteors/hour at peak normally, but at peak times of activity in 33 year cycle appears that the sky is lit with fireworks.
• Description: Bright and fast moving often with trails.

See also Leonid meteor shower

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DECEMBER
The Geminids

• Appear: Both latitudes
• Radiant: Gemini
• Occur: 8th-18th December
• Peak: 13th December
• Maximum Activity: 100 meteors/hour at peak
• Description: Second best meteor shower of the year. Meteors are very bright.

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Data compiled from Eyewitness Handbook: Stars and Planets

See also:
http://stardate.org/

The process by which space debris becomes terrestrial debris occurs in three stages.

A meteoroid is a small stony or metallic particle (typically smaller than a grain of sand) moving in orbit around the sun. Should it be captured by Earth's gravity and pulled into the atmosphere, it becomes a "shooting star" or meteor as it is consumed in its fiery plunge to Earth. If the original meteoroid is sufficiently large that some of it survives the process of ablation and reaches the ground, it is then known as a meteorite.

Meteorites are distributed uniformly around the planet. However, those people who make it their (lucrative) profession to locate such items usually find themselves in Antarctica at some point. There, pristine ice fields make meteorites readily visible, and the extreme cold aids in keeping them free of microorganisms and other terrestrial contaminants.

Me"te*or (?), n. [F. m'et'eore, Gr. , pl. things in the air, fr. high in air, raised off the ground; beyond + , , a suspension or hovering in the air, fr. to lift, raise up.]

1.

Any phenomenon or appearance in the atmosphere, as clouds, rain, hail, snow, etc.

Hail, an ordinary meteor. Bp. Hall.

2.

Specif.: A transient luminous body or appearance seen in the atmosphere, or in a more elevated region.

The vaulty top of heaven Figured quite o'er with burning meteors. Shak.

⇒ The term is especially applied to fireballs, and the masses of stone or other substances which sometimes fall to the earth; also to shooting stars and to ignes fatui. Meteors are often classed as: aerial meteors, winds, tornadoes, etc.; aqueous meteors, rain, hail, snow, dew, etc.; luminous meteors, rainbows, halos, etc.; and igneous meteors, lightning, shooting stars, and the like.

 

© Webster 1913.