Taurids

Not to be confused with Beta Taurids.
Taurids
Parent body 2P/Encke
Radiant
Constellation Taurus
Properties
Occurs during Southern: Sep 10 – Nov 20
Northern: Oct 20 – Dec 10
Date of peak Southern: Oct 10
Northern: Nov 12
Velocity 28 km/s
Zenithal hourly rate 5

The Taurids are an annual meteor shower associated with the comet Encke. They are named after their radiant point in the constellation Taurus, where they are seen to come from in the sky. Because of their occurrence in late October and early November, they are also called Halloween fireballs.

Encke and the Taurids are believed to be remnants of a much larger comet, which has disintegrated over the past 20,000 to 30,000 years,[1] breaking into several pieces and releasing material by normal cometary activity or perhaps occasionally by close encounters with the tidal force of Earth or other planets (Whipple, 1940; Klačka, 1999). In total, this stream of matter is the largest in the inner solar system. Since the meteor stream is rather spread out in space, Earth takes several weeks to pass through it, causing an extended period of meteor activity, compared with the much smaller periods of activity in other showers. The Taurids are also made up of weightier material, pebbles instead of dust grains.[2]

Appearance

Typically, Taurids appear at a rate of about 5 per hour, moving slowly across the sky at about 17 miles per second (27 kilometers per second), or 65,000 miles per hour.[2] If larger than a pebble, these meteors may become bolides as bright as the moon and leave behind smoke trails.[2]

Due to the gravitational perturbations of planets, especially Jupiter, the Taurids have spread out over time, allowing separate segments labeled the Northern Taurids (NTA) and Southern Taurids (STA) to become observable. The Southern Taurids are active from about September 10 to November 20, while the Northern Taurids are active from about October 20 to December 10. Essentially these are two cross sections of a single, broad, continuous stream in space. The Beta Taurids and Zeta Perseids, encountered by the Earth in June/July, are also cross sections of the stream that approach from the Earth's daytime side and, as such, cannot be observed visually in the way the (night-time) Northern and Southern Taurids of October/November can. Astronomers Duncan Steel and Bill Napier even suggest the Beta Taurids could be the cause of the Tunguska event of June 30, 1908.[3]

In 1962 and 1963, the Mars 1 probe recorded one micrometeorite strike every two minutes at altitudes ranging from 6,000 to 40,000 km (3,700 to 24,900 mi) from Earth's surface due to the Taurids meteor shower, and also recorded similar densities at distances from 20 to 40 million kilometres (12,000,000 to 25,000,000 mi) from Earth.[4][5]

The Taurid stream has a cycle of activity that peaks roughly every 2500 to 3000 years,[3] when the core of the stream passes nearer to Earth and produces more intense showers. In fact, because of the separate "branches" (night-time in one part of the year and daytime in another; and Northern/Southern in each case) there are two (possibly overlapping) peaks separated by a few centuries, every 3000 years. Some astronomers note that dates for megalith structures such as Stonehenge are associated with these peaks. The next peak is expected around 3000 AD.[3]

The Taurids also have more frequent peaks which may result from a heavier concentration of material in the stream, which only encounter Earth during some passes.

Fireballs

In 1993, it was predicted that there would be a swarm of activity in 2005.[2] Around Halloween in 2005, many fireballs were witnessed that ruined people's night vision.[2] Astronomers have taken to calling these the "Halloween fireballs."[2]

During the Southern Taurid meteor shower in 2013, fireball sightings were spotted over southern California, Arizona, Nevada, and Utah.[6]

Meteor impact on the Moon

An impact event was observed by NASA scientist Rob Suggs and astronomer Bill Cooke on November 7, 2005, while testing out a new 10-in telescope and video camera they had assembled to monitor the moon for meteor strikes.[7] After consulting star charts, they concluded that the impact body was probably part of the Taurid meteor shower. This may well be the first recording of this type of lunar event which some have claimed to have witnessed in the past.[8]

References

  1. ↑ Babadzhanov, P. B.; Williams, I. P.; Kokhirova, G. I. (2008). "Near-Earth Objects in the Taurid complex". Monthly Notices of the Royal Astronomical Society. 386 (3): 1436–1442. Bibcode:2008MNRAS.386.1436B. doi:10.1111/j.1365-2966.2008.13096.x.
  2. 1 2 3 4 5 6 Dr. Tony Phillips (2005-11-03). "Earth is orbiting through a swarm of space debris that may be producing an unusual number of nighttime fireballs". NASA Science News.
  3. 1 2 3 Meteor Shower Promises Seven Shooting Stars an Hour – National Geographic News (November 7, 2003)
  4. ↑ Robbins, Stuart (2008). ""Journey Through the Galaxy" Mars Program: Mars ~ 1960-1974". SJR Design. Retrieved 2014-01-26.
  5. ↑ Mihos, Chris (11 January 2006). "Mars (1960-1974): Mars 1". Department of Astronomy, Case Western Reserve University. Retrieved 2014-01-26.
  6. ↑ Sky News US Team (2013-11-07). "Meteor 'Fireball' Lights Up California Sky". news.sky.com. London, UK: BSkyB. Retrieved 2013-11-07.
  7. ↑ BBC News: Nasa team sees explosion on Moon (3 January 2006)
  8. ↑ An Eyewitness Impact Debunked

Proc. Amer. Phil. Soc., 83, 711–745.

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