Named after the International
Scientific Optical Network
where it was discovered
An icy body
to Sun displays
tail (or tails).
word "comet" comes from
the Greek word for "hair.”
Our ancestors thought comets
were stars with what looked like
flowing hair trailing behind.
COMETS: “DIRTY SNOWBALLS”
are loose collections of
ice, dust, and small rocky
particles whose orbits are usually
very long, narrow ellipses.
STRUCTURE OF A COMET
A Comet‟s Head
layer= Coma (water vapor,
CO2, and other gases)
inner core= Nucleus
(frozen ice, gas and dust )
a comet approaches the sun and heats
up, some of its gas and dust stream
outward, forming a tail.
Most comets have 2 tails:
gas (ion), tail
Tails point away from the sun because of
the force of the solar wind.
A comet‟s tail can be more than 100 million
10 km “Dirty Snowball”
Cloud of evaporated ices and ions
may be 100,000 km in diameter
Always points away from Sun
Solar Wind and Radiation Pressure
THE OORT CLOUD
1950 Jan Oort noticed that
no comet has been observed with
an orbit that indicates that it came
from interstellar space,
there is a strong tendency for
aphelia of long period comet orbits
to lie at a distance of about 50,000
there is no preferential direction
from which comets come.
ORIGIN OF COMETS
comets are found in 2 regions of
the solar system: Kuiper belt and Oort
Kuiper belt-doughnut-shaped region that
extends beyond Neptune‟s orbit to about
100 times Earth‟s distance from the sun.
Oort cloud-spherical region of comets
that surrounds the solar system out to
more than 1,000 times the distance
between Pluto and the sun.
So what's special about it?
It is thought to be from the Oort cloud
It will travel very close to the sun (0.072 AU),
nearly 14 times closer to the sun then we are!
If it doesn't break apart, it may be as bright as
the Full Moon
It will be visible for several months
The entire globe will be able to see it
WHEN FIRST SIGHTED
sighted it was
from earth in
WHEN FIRST SIGHTED
on the reverse
fainter than the
dimmest star we
can see with our
―On Sept. 21,2012 two amateur astronomers from
Russia spotted what appeared to be a comet in images
taken by a 16-inch (0.4-meter) telescope that is part of
the worldwide International Scientific Optical Network,
or ISON, from which the object draws its name.‖
Comet ISON discoverers Artyom Novichonok (left) and Vitali Nevski
Comet ISON — officially designated C/2012 S1 — may
become one of the most dazzling shows in decades
when it nears our sun later this year. Like all comets,
ISON is a clump of frozen gases mixed with dust. Often
described as “dirty snowballs,” comets emit gas and
dust whenever they venture near enough to the sun as
that icy material transforms from a solid to a gas, a
process known as sublimation. Jets powered by
sublimating ice also release dust, which reflect sunlight
and brightens the overall look of the comet in the sky.
ISON on February 4, March 4, April 3, and May 4, 2013
In late November 2013, its icy material will sublimate
and release large quantities of dust as the surface
erodes under the sun‘s immense solar heat. During this
time, the comet may become bright enough to admire
with little to no astronomy training and could
potentially be viewable for star-watching in the
Northern hemisphere during the day.
Comet ISON is believed to be
making its first trip to the sun,
and so it is hoped to still have
most of its volatiles intact.
Volatiles are the substances
which heat up and blast off the
comet‘s nucleus to form the
wispy comet tail which an stretch
for millions of kilometers through
Comet ISON, discovered by Russian scientists, will be
visible in India towards the end of 2013. Experts have
opined that the comet that will be seen above the western
horizon after sunset is likely to be visible to the naked eye
and could well be brighter than the Moon.
In 2013, astronomy enthusiasts in India would
be privileged to witness a great comet through
naked eyes. In November-December, we will be
able to see Comet ISON.
Comets are often referred as ―dirty snowballs‖ because
they consist of a mixture of ice (both water and frozen
gases) and dust. Astronomers believe these celestial
bodies are made up of material left over from the
formation of the Solar System almost five billion years
Interestingly, comet ISON is following a very
similar path to the famous comet of 1680, which
was bright enough to be visible in the middle of the
Comet ISON that was discovered in September of 2012.
is on somewhat the same trajectory as another famous
Comet called the Great comet of 1680 to which a lot of
artwork is dedicated, since it was such a big spectacle
back then. If it holds together on its journey around the
Sun, it will prove to be the brightest Comet seen in our
Most comets reside in a
System called the „Oort
Cloud‟ Comet ISON is
likely making its first trip
to the inner solar system
ever, coming to us from
the remote Oort Cloud, a
locker” of trillions of comets gathered into a thick
spherical halo at the fringes of the solar system. The near
edge of the Cloud is some 5,000 A.U.s from the sun or 465
billion miles away. Far from the sun, an icy comet‟s
temperature hovers around absolute zero (-459 F). If you
could see it up close, there would be no fuzzy coma or tail
just an inert hunk of dark ice
For most of 2013, Comet ISON will be a faint
telescopic object but its brightness increases
enormously as it approaches the Sun late
2013. Comet ISON reaches perihelion on Nov
29 when it passes within 0.012 AUs of the
Sun. At that time the comet will appear near
the Sun, but it could be as bright as the Full
Moon and visible in the daytime. Quickly
moving into the evening sky, ISON could put
on a spectacular show for much of December.
On Dec 27, the comet makes its closest
approach to Earth at a distance of 0.429 AUs.
It will then be 80° from the Sun and well
placed in northern skies during the
Comet C/2012 S1
to become a great
comet late in 2013 /
early in 2014.
Comet ISON (C/2012
S1) has the potential
to become a very
bright object that will
be well placed for
viewing in late 2013.
NASA's iconic Hubble Space Telescope has
captured the clearest view yet of Comet
ISON, which experts believe could become
one of the brightest comets ever seen when
it lights up the sky later this year.
BACK ON JAN. 30, NASA‘S SWIFT SPACECRAFT AIMED ITS
POWERFUL, MULTI-WAVELENGTH EYES AT THE COMET WHEN
IT WAS STILL NEAR JUPITER. EVEN AT THAT DISTANCE,
SOLAR HEATING VAPORIZED ENOUGH ICE FOR ISON TO SPEW
OUT 112,000 LBS. (51000 KG) OF DUST A MINUTE.
Position of Comet „ISON‟ during 20th March 2013 - 20th
Morning of 15th October‘13 - Eastern Sky
Viewing of comet is considered to be a treat for eyes for anyone, and it seems that the
reality is going to get fulfilled, as comet ISON is going to come in the inner solar system.
Comet ISON and Mars November 1, 2013, just before
Sunrise in the eastern sky (Northern Hemisphere). This
occurs slightly after the long-standing ISON-Mars
conjunction in earlier Leo.
As plotted by the Jet Propulsion Laboratory's "Horizons" system,
Comet ISON (C/2012 S1) will pass very close to the Sun — but not
crash into it — in late November 2013. At that time it might be at
least magnitude –10 — bright enough to be spotted despite very
strong solar glare.
In fact, the geometry could make C/2012 S1 a "dream comet," as
one eager sky-watcher has commented, because it will swing just
40 million miles (0.4 astronomical unit) from Earth a few weeks
after perihelion, when it will be high in moonless, northern skies
after sunset and that it could remain visible to the unaided eye
from early November to the first weeks of 2014.
Scenario in early morning sky before sunrise on 27th
November‘13 – Moon, Saturn, Mercury and Comet ISON
National Geographic has stated on their official site that the
comet WILL be the brightest in human history and will be
brighter than a full moon.
The possibility of the comet being visible in the daytime skies will make it
one of the most exciting comets to whiz past the earth in a long while.
At its perihelion (its closest point to the sun), due on November 28,
2013, the comet will come within 18,00,000 kilometers of the sun‘s
surface and could evolve into a dazzling celestial body, possibly bright
enough to be visible in broad daylight
On December 8, Comet ISON crosses into the northern sky. It should
shine brighter than 1st magnitude and perhaps sport a spectacular tail.
Northern Hemisphere viewers will get increasingly better views as
Orbital position of C/2012 S1 on 11 December 2013 after perihelion
Simulation of the orbit of comet C/2012 S1 ISON between 1 November
2013 and 12 December 2013. Earths orbit is indicated in red, and red
crosses mark the location of Earth as ISON makes it's close approach.
There's been some speculation on the web that (a) we will cross comet
C/2012 S1 ISON's tail, and (b) we will get meteor showers from it.
Comet tails point way from the Sun, due to the solar wind blowing the
dust and gas away.
The comet will be best seen just before dawn during midDecember. The huge tail will loom in the eastern sky. The
tail may be stretched up to BoÖtes or the Handle of the Big
Dipper. The comet can be nicely observed, climbing higher
in the eastern pre-dawn sky. The comet will shine within
6th magnitude until the month’s end, and so the end of the
year. The comet will move from Serpent’s Caput to Draco
throughout the month. It will be 5 degrees from the Great
Hercules Globular (M13) on December 22nd.
It might eject vast jets of gas and dust and be
spectacular with a fine tail and even become one of
the finest comets ever witnessed by mankind.
The comet may or may not be very bright;
it's tail may be long or short
It will definitely improve our understanding about
May be life on Earth also
Comet 2013 A1 (Siding Spring) will pass
within ~130,000 km on Oct. 19, 2014