AMERICAN CHEMICAL
SOCIETY
Contact: Sharon Worthy
202-872-4371
s_worthy@acs.org
EDITOR’S NOTE: Kids and adults nationwide will take part in National
Chemistry Week activities Oct. 19-25, an annual event sponsored by the
American Chemical Society, the world’s largest scientific society. This year’s
theme — “Earth’s Atmosphere and Beyond!” — was selected to help celebrate
the 100th anniversary of flight. For more information about National Chemistry
Week, visit our Web site at chemistry.org/ncw.
FOR IMMEDIATE RELEASE
Beyond earth’s atmosphere!
This year’s ‘close’ encounter with Mars sparked the imagination and interest of people
everywhere, from wide-eyed youngsters to life-long astronomers. Unraveling the
mysteries of our solar system takes dedication, patience and chemistry! To underscore
our fascination with space, this year’s theme for National Chemistry Week (Oct. 19-25)
is “Earth’s Atmosphere and Beyond!” The annual weeklong celebration of chemistry and
its role in our lives is sponsored by the American Chemical Society, the world’s largest
scientific society.
Nine planets orbit the sun counter-clockwise in our solar system. The planets closest to
the sun make up the inner solar system — Mercury, Venus, Earth and Mars. The outer
solar system is comprised of Jupiter, Saturn, Uranus, Neptune and Pluto. The inner and
outer solar systems are separated by the asteroid belt.
Rocky and small
The rockiest planets are Mercury, Venus, Earth and Mars. Along with tiny Pluto, they
also are the smallest planets. Each of these planets is less than 8,000 miles in diameter,
with Pluto coming in at less than 2,300 miles in diameter. In contrast, the giant planets —
Jupiter, Saturn, Uranus and Neptune — are primarily gaseous and have diameters ranging
from about 32,000 miles for Uranus to nearly 89,000 miles for gargantuan Jupiter, which
is more than 300 times as massive as our home planet of Earth.
– more –
A nonprofit organization with a membership of more than 161,000 chemists and chemical engineers, the American Chemical Society
publishes scientific journals and databases, convenes major research conferences, and provides educational, science policy and
career programs in chemistry. Its main offices are Washington, D.C., and Columbus, Ohio.
Mercury
The closet planet to the sun, Mercury is the eighth largest of the nine planets in our solar
system. Between 1974-1975, NASA’s Mariner 10 spacecraft mapped nearly half of
Mercury’s rocky surface, revealing that the planet was heavily cratered and has no
significant atmosphere. Mercury’s north pole may have ice and it is believed that the
craters protect the ice from the sun’s heat. It orbits the sun every 88 Earth days. NASA’s
upcoming MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and
Ranging) Mission, which will enter Mercury’s orbit, launches in May 2004.
Venus
Except for the sun and our moon, Venus — the second planet from the sun and the sixth
largest — is the brightest object in our sky. Blanketed with clouds made of sulfuric acid,
Venus has a surface temperature of approximately 700 degrees Fahrenheit, making it too
hot for rain. Over 20 spacecraft have mapped its surface, including Mariner 2, Mariner
10 and Magellan in 1989. Venus does not have a moon and it orbits the sun every 224
Earth days.
Earth
Ahhh, home sweet home! Our host planet is the third one from the sun, the fifth largest
and supports all types of life. Our world’s atmosphere is primarily composed of nitrogen
(77 percent) and oxygen (21 percent), with smaller amounts of other gases. Water, which
is necessary for life, as we know it, covers 71 percent of Earth’s surface. Interestingly,
Earth’s core temperature is approximately 10,000 to 13,000 degrees Fahrenheit, which is
about as hot as the surface of the sun. Of course the sun’s core is much hotter than
Earth’s.
Mars
The so-called “Red Planet” is the fourth from the sun and the seventh largest. Mars is
cold and believed to be lifeless, with permanent ice caps of water and carbon dioxide at
both poles. The average temperature on the planet is estimated at –67 Fahrenheit. It also
experiences frequent massive dust storms, some of which can cover nearly the entire
planet. Mars does have two tiny moons orbiting close to its surface. They are Phobos and
Deimos. Earlier this year Mars was only a ‘mere’ 35 million miles from Earth — just a
stone’s throw in astronomical terms — the closest it has been to us in almost 60,000
years. Mars orbits the sun every 687 Earth days.
Pluto
If any planet has a right to an inferiority complex, it’s Pluto. Not only is it the smallest
and farthest from the sun, it’s never been visited by one of our space probes. Although it
does have one moon, some people still think it should be considered a big asteroid instead
of a planet! Since it was discovered in 1930, scientists have learned that Pluto has an odd
elliptical orbit, which at times makes it closer to the sun than its nearest planetary
neighbor, Neptune. It’s believed that Pluto’s atmosphere has nitrogen with traces of
methane and carbon monoxide.
– more –
BIG and full of gas, they’re ringers!
The giant planets — Jupiter, Saturn, Uranus and Neptune — are mostly made of
hydrogen and helium gases. Surrounding them are rings, primarily a combination of dust,
rocks, frozen gases and lumps of ice. They also have multiple moons.
Jupiter
Jupiter, the fifth planet from the sun and the largest of all, is about 90 percent hydrogen
and 10 percent helium and orbits the sun once every 12 Earth years. More than 300 times
more massive than Earth, the planet is famous for its Great Red Spot, which is so large
that two Earths would fit in it. The spot is thought to be a high-pressure weather system.
Befitting such a behemoth, astronomers so far have discovered 61 celestial bodies
orbiting Jupiter, including four large moons, three of which are larger than Earth’s moon.
The Galileo spacecraft was launched in 1989 from the Space Shuttle Atlantis to explore
Jupiter. It ended its mission on September 21, 2003, with a planned impact with the
planet. The probe had been in orbit around Jupiter for nearly eight years.
Saturn
Saturn, our solar system’s second largest planet and the sixth from the sun, is most
famous for its beautiful rings. Italian physicist and astronomer Galileo, using the world’s
first telescope, discovered the rings in 1610. Saturn has at least 31 satellites that have
been discovered so far. Its largest moon, Titan, is larger than Mercury. Three spacecraft,
Pioneer 11, Voyager 1 and Voyager 2, have conducted flybys of Saturn. NASA’s Cassini
spacecraft is scheduled to go into orbit around the planet next summer.
Uranus
The planet that spins differently from the others, Uranus, is the seventh planet from the
sun and the third largest. It is tilted so much that what is thought to be its south pole is
really pointed toward the sun. (There’s an ongoing debate among scientists whether it’s
the south or north pole.) Unlike the other planets that have more or less a vertical rotation
— as seen from the sun’s point of view — Uranus essentially rotates on its side. Uranus
has 15 known moons, orbits the sun every 84 Earth years and has an atmosphere of
mostly hydrogen and helium, with traces of methane. Voyager 2 flew by the planet in
1986.
Neptune
Named for the mythical Roman god of the Sea, Neptune is the fourth largest planet and is
the eighth from the sun. However, because of Pluto’s elliptical orbit, Neptune is
sometimes the most distant of the nine planets. Only one spacecraft, Voyager 2, has ever
flown by Neptune and its eight moons. Neptune’s atmosphere consists of methane,
hydrogen and helium. It orbits the sun every 165 Earth years.
– more –
Sol
A brief discussion of our solar system wouldn’t be complete without an understanding of
the middle-aged star (about 2.5 billion years old) around which the planets revolve. The
sun, also called Sol in Roman mythology or Helios in Greek mythology, is approximately
75 percent hydrogen and 25 percent helium. But it is slowly changing its composition as
nuclear fusion reactions in the sun’s center convert hydrogen to helium. Fortunately, it
will take another 2.5 billion years or so before the sun uses up all its hydrogen and starts
dying off. The core temperature of the sun is estimated to be 15.6 million degrees Kelvin
— about 28 million degrees Fahrenheit. Although our sun is pretty ordinary by galactic
standards — it is of average size and brightness — it still dwarfs everything else in our
solar system. More than a million Earths could be placed inside the sun with plenty of
room leftover.
Create your own craters
Our Earth and moon, and many of our neighboring planets and their moons, have been
struck lots of times by asteroids, comets and meteorites. The impacts can leave craters
that range from small to huge. More than 100 impact craters have been identified so far
on Earth. But our moon has millions of craters. If you look at the full moon on a clear
night, you can actually see the craters.
Here’s an experiment that will show how impact craters are formed. You will need
newspaper, a small plastic butter or margarine tub or paper bowl, a ruler, flour, paprika
and small stones (a littler larger than a pea). Here are the steps:
(1) Cover the floor of your work area with newspapers. (You might even want to do
this activity outside). Completely fill the bowl with flour then use the ruler to
scrape across the flour surface to make it very smooth. Be careful not to inhale the
flour.
(2) Sprinkle paprika over the surface of the flour.
(3) Stand directly over the bowl and drop a small stone “meteorite” into the bowl.
Did the stone make a crater in the flour’s surface? If not, try dropping a different
size stone or dropping it from a different height.
(4) Can you still see the stone after it hits? Many meteorites also disappear, but in a
different way. Meteorites have so much energy when they collide with a planet or
a moon, they explode, creating giant craters that can be several miles wide! Some
meteorites even vaporize when they hit.
(This activity is taken from “The Best of WonderScience,” a collection more than 600
science experiments designed from grades K-8, published by the American Chemical
Society.)
To learn more about this year’s National Chemistry Week theme ─ “Earth’s Atmosphere
and Beyond!” ─ visit chemistry.org/ncw.
For additional information about the planets and the solar system, visit
sseforum.jpl.nasa.gov.
###
#13585
Released 09/29/2003