Comets

CometsHistory and Exploration

ImagineYou are living on the plains 5000 years agoEach evening as it gets dark, you go out and watch the sky

The Sun SetsAnd the same stars appear

Night after night

They shift just a little

A wanderer appears

The Moon

Year after year

Every year, the same stars mean Spring

the river will flood

get the harvest in before the locusts come

The skies are a guide

A calendar,

Until something new appears

Something out of place

What could it Mean??

Disaster!

destruction, storm and frost

Yakut legend in ancient Mongolia called comets "the daughter of the devil," and warned of destruction, storm and frost, whenever she approaches the earth.

http://deepimpact.umd.edu/science/comets-cultures.html18

War

http://www.nasa.gov/mission_pages/deepimpact/media/f_ancient.htmlTypes of cometary forms, illustrations from Johannes Hevelius' Cometographia (Danzig, 1668)19

Bayeux Tapestry

http://www.bayeuxtapestry.org.uk/ Long Live The King - Scene 1

http://www.bayeuxtapestry.org.uk/ Long Live The King - Scene 1

Halleys comet is top, center, the day Edwards funeral and Harolds corronation. The ships at bottom portend the coming Norman invasion.Supposedly, William the conqueror saw the comet and took it as a sign that it was time to invade England.

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A disaster for every comethttp://www.nasa.gov/mission_pages/deepimpact/media/f_ancient.html

http://www.nasa.gov/mission_pages/deepimpact/media/f_ancient.html

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But then

Edmund Halley convinced Issac Newton to work out the orbits of several comets, and realized the comets of 1531, 1607 and 1682 were actually the same comet!

Would return in 175822

Comets are solar system objects! Predictable, and understandable!Exciting, and NOT a disaster!

Punch, 1909

http://solarsystem.nasa.gov/scitech/display.cfm?ST_ID=20523

Comet hunting in the 18th century

Messiers list of 110 fuzzy objects that werent comets (also found 44 comets, about 20 of which were true discoveries)24

Comet observing in the 19th CenturyDonatis comet, 1858Most beautiful comet

This image is from Harvard, but many observations were made at the Detroit Observatory

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Detailed orbital elements

Comet AnatomyParts visible only when close to the Sun.

IonsAtoms & molecules missing electronsOften emit light -> Spectroscopy!

20th century observationsComet 1913 f, DelavanPublications of the Astronomical Observatory of the University of Michigan ; v. 3, Ann Arbor : The University, 1923

Captured using the single prism spectrograph on the 34-1/2 at the Detroit Observatory. http://articles.adsabs.harvard.edu//full/1923POMic...3..264C/0000295.000.html29

Disaster!Cyanogen gas found in Halleys cometEarth would pass through the comets tail!!

http://www.wondersandmarvels.com/2010/12/con-men-and-comets.html

http://www.wondersandmarvels.com/2010/12/con-men-and-comets.html

Mass of Halleys comet:1014 kgMass of Earths atmosphere: 5x1018 kgThe amount of air on Earth is 50,000 times greater than the entire mass of Halleys comet!

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Questions only comets could answerHow do planets / the solar system form?What materials were available to build planets?Where did Earths water come from?

Goodrich & Ward, The Formation of Planetesimals 1973

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ICEInternational Sun-Earth Explorer was designed to study the Sun-earth environment, but had the chance to fly through Giacobini-Zinners tail! Pelted by dust grainsConfirmed spectroscopic measurements

GiottoApril 1986

http://neo.jpl.nasa.gov/images/halley.html

Lumpy, dark, lots of organics, lots of water, localized jets33

StardustFlew through coma of Wild 2Returned a sample

StardustReturned a sample

Life from comets?Comets may have brought the water, carbon, nitrogen, and organic molecules in to the inner solar system!Stardust samples included glycerin!

Matthew Genge / Imperial College London

journal Meteoritics and Planetary Science; August 2009, Jamie Elsilahttp://www.nasa.gov/mission_pages/stardust/news/stardust_amino_acid.htmlan amino acid used to build proteins36

Deep ImpactImpacted Temple 1Comet was softer than expected!

ISONsungrazerMost observed comet everIn addition to ground based observers, including amateurs, many spacecraft watched the comet

Mike Hankey, Nov. 15, 2013, Auberry, California.

End of ISON

Nov 28, 2013http://sohowww.nascom.nasa.gov/hotshots/index.html/

RosettaRendezvous on January 20, 2014 with comet 67P/ChuryumovGerasimenkoObit until November, then send a lander

DisosaursSpaceplace.nasa.gov

Comets can bring disaster41

Hakutake

http://www.twanight.org/newTWAN/photos.asp?ID=3002020

But most bring beauty42

Waiting for the next Hale Bopp

http://www.twanight.org/newTWAN/guests_photos.asp?ID=5001238

And we wouldnt be here without them43