Sep 7th: The Tale of the Disappearing Comet

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Podcaster: Richard Drumm
Title:
Space Scoop: The Tale of the Disappearing Comet

Organization:365 Days Of Astronomy

Link : astrosphere.org ; http://unawe.org/kids/unawe1724/

Description: Space scoop, news for children.

Jets of gas spinning with the stars

Bio: Richard Drumm is President of the Charlottesville Astronomical Society and President of 3D – Drumm Digital Design, a video production company with clients such as Kodak, Xerox and GlaxoSmithKline Pharmaceuticals. He was an observer with the UVa Parallax Program at McCormick Observatory in 1981 & 1982. He has found that his greatest passion in life is public outreach astronomy and he pursues it at every opportunity.

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by — no one. We still need sponsors for many days in 2016, so please consider sponsoring a day or two. Just click on the “Donate” button on the lower left side of this webpage, or contact us at signup@365daysofastronomy.org.

Transcript:
This is the 365 Days of Astronomy Podcast. Today we bring you a new episode in our Space Scoop series. This show is produced in collaboration with Universe Awareness, a program that strives to inspire every child with our wonderful cosmos.

The Tale of the Disappearing Comet

Many times a year, the night sky is lit up by many fast moving spots of light. You may know these as “shooting stars”, but they don’t really have all that much to do with stars.

They are small bits of rock as small as a grain of sand burning up in our atmosphere. We call them “meteors”.

The bits of rock are called “meteoroids” before they hit our atmosphere, “meteors” while they are streaking through the atmosphere. Those few that make it to the surface are called “meteorites” after they hit.

Sometimes, meteors rain down on Earth in groups. This is called a “meteor shower”.

Meteor showers are caused by comets. Comets are made of space dust, rock and ice. When they travel close to the Sun the heat causes the ice to evaporate.

Small bits of space dust and rock escape, the dust sometimes creates a beautiful glowing tail.

The rocky bits that the comet leaves behind stay in the comet’s orbital path around the Sun like a gravel road running through the countryside.

When the Earth travels through the path of a comet, the particles burn up in our atmosphere as a meteor shower. There are a few nice meteor showers each year.

Go outside after midnight to see them when they are happening and enjoy the show! Just lie down on a blanket or a chaise lounge and keep your eyes open. You won’t need a telescope to see them, just your open eyes.

The Leonids, which happen around November 17th, and the Perseids, which happen around August 12th, are the major showers. They come back each year at the same date.

One minor meteor shower is called the “Phoenicids”. It happens around December 5th and is mostly visible from the Southern Hemisphere.

The Phoenicids are named for the constellation Phoenix in the southern skies.

This shower unexpectedly lit up our skies with 100 meteors an hour back on December 5th, 1956. The Japanese Antarctic Research Expedition, traveling to Antarctica through the Indian Ocean discovered the shower that night as they stood on the deck of their ship, the “Soya”.

And then the meteor shower never returned.

Astronomers were left wondering: where did the Phoenicids come from and where did they go?

To find the answer to this, they went in search of a missing comet called Comet Blanpain.

On November 28, 1819 French astronomer Jean-Jacques Blanpain of Marseille discovered it and it was named Comet Blanpain after him. He saw it in the morning skies in the constellation Virgo.

There was no tail observed, so this isn’t one of the beautiful photogenic comets that we think of when we hear the word “comet”.

It was also independently discovered on December 5th by J.L. Pons in Marlia, Italy, but he was too late to have it named for him. And by the end of the year the already faint comet had gotten lost in the glare of the full Moon.

The comet was recovered in January of 1820 after the Moon had moved on, but the comet was very, very faint. It was moving away from the Sun and getting ever fainter, and had moved into a region of nebulae and it was lost.

Enough observations of it had taken place for an approximate orbit to be calculated.

Time passed. Wars came & went. More time passed.

In 2003 an asteroid was spotted by our friends at the Catalina Sky Survey. It was traveling along the same path as the comet and was called 2003 WY25 at first. It turns out this was the remains of the long-lost Comet Blanpain!

The larger dust particles and rocky bits that have escaped the comet still float through space as that gravel road I talked about before. And the asteroid follows the same path that Comet Blanpain once traveled.

The ice sublimated into gas and it and the smaller dust particles were blown away by the solar wind and are headed out to the Kuiper Belt or the Oort Cloud.

There was a small coma or gas cloud around the comet’s nucleus when it was imaged by the Pan-STARRS team in July 2013, so it isn’t completely dead. A few more rocks and bits of sand can fall off and pave that gravel road.

It now has the official designation of 289P/Blanpain. The P stands for “Periodic” as it’s a comet that has a calculable orbital period as it orbits the Sun.

When the Earth collides with the trail, the particles light up the sky as the Phoenicid meteor shower!

Hey, Here’s A Cool Fact:

The material that creates a meteor shower all comes from the same direction in the sky. Most meteor showers are named after the constellation that they seem to come from.

It’s just an optical effect caused by the orbital velocity of Earth and the velocity of the meteoroids themselves. It’s like when it’s snowing and you look up.

It looks like the snowflakes are radiating from a single point in the sky. But they’re all falling in parallel paths of course. If you walk forward the radiant point for the snowflakes shifts forward too.

But, of course, in the case of a meteor shower the stars in the constellation are actually much farther away from us.

Thank you for listening to the 365 Days of Astronomy Podcast!
End of podcast:

365 Days of Astronomy
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The 365 Days of Astronomy Podcast is produced by Astrosphere New Media. Audio post-production by Richard Drumm. Bandwidth donated by libsyn.com and wizzard media. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org.  This year we will celebrate more discoveries and stories from the universe. Join us and share your story. Until tomorrow! Goodbye!

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