Comets & Halley’s Comet

By: Jennifer Wotczak

Agenda

1. Comets2. Comet Makeup3. Comet Orbit4. Comets in History5. Halley’s Comet6. Conclusion 7. Bibliography

Southern Arizona in 1986

Comets Fast Facts • *Dirty Snowballs – Fred

Whipple (icy dirtballs)

• Small icy solar system

body that outgasses:

when ORBITING THE

SUN

• Dust, ice, carbon

dioxide, ammonia,

methane, and more!

• Left over from the

formation of stars &

planets billions of years

ago

Physical Characteristic • Solid nucleus (core) mostly ice, dust,

frozen water, ammonia, carbon dioxide,

carbon monoxide & methane

• As comet approaches the sun nuclear

surface turns into gas forming a cloud

known as a COMA

• Solar radiation pushes particles away

formation of DUST TAIL

• Charged particles convert some gases

into ions ION TAIL

Quick Picture

More about the Makeup

• Most comets nuclei measure 16 km

(10 miles)

• Some comets have tails that can

reach 1.6 million km (1 million miles)

wide

• & tails reaching 160 million km (100

million miles) long

• Comets are visible with the naked eye

when they pass close to the sun

comas & tails reflect sunlight & glow

energy absorbed from sun.

Let’s Talk Orbit

More about Orbit

Orbital Characteristic• Comets are classified based on the

duration of their solar orbit

• Short-period orbit 200 years or less

• Long-period orbits more than 200 years

• Single-apparition comets not bound to

the sun, orbit out of the solar system

• Scientist have found comets in main

asteroid belt might be key source of

water for inner terrestrial planets

• Long-period comets thought to come

from Oort cloud

Oort Cloud • Spherical cloud of

predominately icy

planetesimals

• Surrounds the Sun up to

50,000 AU, almost a light-

year

• Astronomers believe

cloud formed closer to

sun, and was scattered

out by gravitation effects

from the giant plants

Halley’s Comet

• Arguable the most famous comet

in the world

• Visible to the naked eye every 76

years roughly (if your lucky it might

appear twice in your lifetime)

• Last appeared in 1986 first time

technology allowed for in depth

study

• Next appear in mid 2061(if you are

20 know, you’ll be 68)

A Bit of Halley History

• Halley’s comet records date

back to 240 BC

• In clear records of the

Chinese, Babylonians, and

medieval Europeans

• PERIODICITY first determined

in 1705: English Astronomer

Edmond Halley

1986• First time we has the technology to

get close to the comet

• When it passed earth in 1986: 5

spacecraft's flew past it & gathered

unprecedented detail

• First time close enough to look past

coma and study nucleus

• Nucleus was equal parts ice & dust

• 80% of ice water

• 15% carbon monoxide

Quick Video

• https://www.youtube.com/watch?v=

C8zV1xiGqf4

Important Take Always• Comets: Ice & Dust balls left over from star

& planetary creation billions of years ago

• Most orbit the sun & when they get close,

nucleus heats up and forms a gas

atmosphere called a coma

• The solar radiation pushes dust & gas off

form dust & ion tail

• Halley’s Comet “Comet of Earth”

• Visible to the naked eye every 76 years

• Hopefully in 2061 we will ALL see Halley!!

Thank you!

Bibliography

• https://solarsystem.nasa.gov/planets/profile.cfm?Object=Comets

• http://www.space.com/53-comets-formation-discovery-and-

exploration.html