2. COMETS
An icy member of our solar system.
Travel in elliptical orbits around the Sun
and follow the basic laws of physics.
Throughout history, people have dreaded
them as omens of human disasters such
as wars of famines.
3. Orbits of Comets
Elliptical Aphelion distance
in Shape
Randomly Comet
oriented
Sun
Earth
Perihelion distance
4. SIGNIFICANCE OF COMETS
.
They are probably the only objects left that
are made out of the original material from
which the whole solar system formed about 5
billion years ago.
Earth, Moon, and other celestial bodies
have all been changed by tectonicprocesses,
erosion, or numerous collisions. Only comets
remain basically asthey were in the
beginning.
5. Plasma Tail
Dust
Tail
Nucleus
Coma
Hydrogen Cloud
6. Comet Structures
Nucleus
.
made of mostly water ice and other frozen gases (the
“snow”) loosely mixed with stony or metallic
solids (the “dirt”).
It has very low density and surface gravity.
The nucleus contains most of the comet's mass but is very
small (about 1 to 10 km across - or more).
Nucleus - Few 10’s of km
7. Coma
Cloud of evaporated ices and ions
may be 100,000 km in diameter.
the roughly spherical blob of gas that
surrounds the nucleus of a comet
Coma - May
be 1000’s of
km
8. Tail
Always points away from Sun
Solar Wind and Radiation Pressure
TYPES:
a. Ion tail: : A tail of charged gases (ions) always faces away from the
sun because the solar wind (ions streaming from the sun at high
velocities) pushes it away (it is also called the plasma tail)
b. Dust tail: a long, wide tail composed of microscopic dust particles
that are buffeted by photons emitted from the Sun; this tail curves
slightly due to the comet's motion. The tail fades as the comet
moves far from the Sun.
11. Origins of Comets
Comets are usually have 2 PERIODS:
1. LONG-PERIOD COMET
• are those that take more than 200 years to revolve once around
the sun or may be a tangent and never come back again. Usually,
these comets come from the Oort cloud.
• This expansive cloud of maybe over 3 trillion comets
encompasses our solar system 18 trillions miles away from the
sun and is believed to be the remains during the creation of the
solar system.
15. The Kuiper Belt Compared Against the Oort
Cloud
Comets come from regions of the outer solar system known as the Kuiper belt
and the Oort cloud.
Oort cloud comets:
( Jan Oort) Kuiper belt comets:
• About a trillion comets
( Gerard Kuiper)
• About a billion comets
• Each comet is typically
more than 10 km across
separated from the next
by more than 1 billion km • About 100,000 comets
more than 100 km across
•Oort cloud comets do
not orbit the Sun in the • Kuiper belt comets orbit
same direction as the the Sun in the same
planets, and orbits can direction (CCW) as the
be pointed in any planets
direction
•Kuiper belt comets lie
•Orbits can span up to
close to the plane of
50,000 AU planetary objects
16. Astronomers have
catalogued about 150
short-period or
periodic comets, that Period Closest
Approach to
have periods of
revolution around the COMET (years) Sun(in AU)
sun of a few years or
decades up to 200 2P/Encke 3.3 0.34
years.
21P/Giacobini- 6.6 1.03
Zinner
14P/Wolf 8.2 2.41
55P/Tempel 33.2 0.98
-Tuttle
1P/Halley 76.0 0.59
18. 2. Coma 3. Close to
forms as a the Sun, tails
1. Far from the comet form.
sun, a comet approaches
consists of a the Sun.
nucleus of frozen
gases and dust.
5. Far from
the sun
4.After going again, coma
around the and tails are
Sun,much gone.
cometary
material
refreezes.
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!
The existence of a dark companion to the sun was prompted, in part, by a study of mass life extinctions throughout the earth’s past geological ages. Since these extinctions occurred periodically, and since one of the most recent (the dinosaurs) seems to have been associated with a major impact event on earth, scientists were led, through a long chain of logic, to propose the Nemesis theory. Can you formulate a chain of arguments that leads from periodic mass extinctions to a dark star hypothesis, given what you have learned from this lesson so far? Try!!