Return of the Leonids

Nov 14, 2006
Return of the Leonids
A Leonid meteor streaks past the Orion Nebula in 2001. Photo Credit: Mark Brown of Alabama.

On Sunday, Nov. 19th, Earth will pass through a stream of debris from comet 55P/Tempel-Tuttle. The result: a shower of Leonid meteors.

"We expect an outburst of more than 100 Leonids per hour," says Bill Cooke, the head of NASA's Meteoroid Environment Office in Huntsville, AL. This pales in comparison to the Leonid storms of 2001 and 2002, when sky watchers saw thousands of meteors. Even so, a hundred per hour would make the Leonids one of the best showers of 2006.

The problem is, you have to be in the right place at the right time to see them.

Earth's encounter with the comet dust is going to be brief—"possibly no more than a few hours long," says Cooke. Forecasters differ on when the outburst will occur. Estimates range from 0445 UT to 0630 UT on Nov. 19th (11:45 p.m. on Nov. 18th to 1:30 am EST on Nov. 19th). The timing favors western Europe, Africa, Brazil and eastern parts of North America: map.

Cooke urges observers to find the darkest possible skies. "These Leonids are going to be faint." Why? "The stream contains very small grains of comet dust. Small grains make faint meteors--it's as simple as that."

Return of the Leonids
A minefield of Leonid debris streams. The streams intersect the plot at nearly right angles, so they resemble 2D clouds rather than 3D filaments. Credit J. Vaubaillon.

The mid-November region of Earth's orbit is littered with debris from Comet Tempel-Tuttle. Every time the comet visits the inner solar system (once every 33 years), it lays down a new stream of dust, pebbles and rock. This creates a sort of "minefield" for Earth to navigate every November.

Not all of these debris streams are alike. For example: "A Leonid stream we hit in 1998 was full of rock-sized debris. They made brilliant fireballs when they hit the atmosphere," recalls Cooke. "The stream we're hitting this year is just the opposite. It's mostly fine dust."

Debris streams are segregated—dusty vs. rocky—by the force of sunlight. Consider the stream directly ahead of us: "It was ejected from the comet in 1933," says Cooke. "At first, the debris was a mixture of many sizes." But as years passed, the smaller particles diverged from the larger ones. Radiation pressure—the delicate pressure of sunlight itself—pushed the light dust onto a collision course with Earth. Heavier rock-sized fragments resisted the pressure and lagged behind.

Perhaps in some future year we'll encounter the larger debris from 1933 and receive an overdue display of fireballs. How would they get here? "Nudged by Jupiter," suggests Cooke. Jupiter's gravity is strong enough to alter the course of heavier fragments. Indeed, by guiding debris toward us, Jupiter is indirectly responsible for many bright Leonid displays in the past.

But this is 2006. So prepare for an outburst of faint Leonids.

Extra: Don't believe everything you read. While meteor forecasters have done a splendid job predicting Leonid outbursts in recent years—sometimes "nailing the peak within minutes"—they could be wrong in 2006. The outburst might happen at an unexpected time or it might be better than expected. Cooke urges enthusiasts everywhere to keep an eye out for Leonid meteors the nights of Nov. 17th – 19th. "The best time to look," he says, "is just before local dawn when the constellation Leo is high in the sky."

Source: Science@NASA, by Dr. Tony Phillips

Explore further: Can astronomy explain the biblical Star of Bethlehem?

add to favorites email to friend print save as pdf

Related Stories

Bright explosion on the Moon

May 17, 2013

For the past 8 years, NASA astronomers have been monitoring the Moon for signs of explosions caused by meteoroids hitting the lunar surface. "Lunar meteor showers" have turned out to be more common than anyone ...

The Orionid meteor shower

Oct 15, 2012

Usually, waking up before sunrise is a good way to get a head start on the day. On Oct. 21st, waking up early could stop you in your tracks.

Shooting for Shooting Stars

Apr 08, 2010

(PhysOrg.com) -- You know them as "shooting stars," or meteors. Space scientists know them as the fiery end of tiny visitors from space. Those momentary streaks of light across the night sky are nothing more ...

Meteor showers in Asia disappoint

Nov 18, 2009

(AP) -- Thousands of stargazers across Asia stayed awake overnight to catch a glimpse of what was advertised as an intense Leonid meteor shower, but the show fizzled rather than sizzled for many because of ...

The 2009 Leonid Meteor Shower

Nov 10, 2009

This year's Leonid meteor shower peaks on Tuesday, Nov. 17th. If forecasters are correct, the shower should produce a mild but pretty sprinkling of meteors over North America followed by a more intense outburst ...

Recommended for you

Can astronomy explain the biblical Star of Bethlehem?

13 hours ago

Bright stars top Christmas trees in Christian homes around much of the world. The faithful sing about the Star of Wonder that guided the wise men to a manger in the little town of Bethlehem, where Jesus was ...

Hubbles spies the beautiful galaxy IC 335

14 hours ago

This new NASA/ESA Hubble Space Telescope image shows the galaxy IC 335 in front of a backdrop of distant galaxies. IC 335 is part of a galaxy group containing three other galaxies, and located in the Fornax ...

Image: Multicoloured view of supernova remnant

Dec 22, 2014

Most celestial events unfold over thousands of years or more, making it impossible to follow their evolution on human timescales. Supernovas are notable exceptions, the powerful stellar explosions that make ...

Ultra-luminous X-ray sources in starburst galaxies

Dec 22, 2014

Ultra-luminous X-ray sources (ULXs) are point sources in the sky that are so bright in X-rays that each emits more radiation than a million suns emit at all wavelengths. ULXs are rare. Most galaxies (including ...

When a bright light fades

Dec 22, 2014

Astronomer Charles Telesco is primarily interested in the creation of planets and stars. So, when the University of Florida's giant telescope was pointed at a star undergoing a magnificent and explosive death, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.