This image shows an oxygen trail created when a small comet was disrupted as it approached our planet on September 15, 1996. This image was taken by the Polar spacecraft's Earth Camera in ultraviolet wavelengths. The oxygen trail has been superposed upon a "Face of the Earth" map of our planet.
Courtesy of Dr. Louis A. Frank, The University of Iowa and NASA
In 1997, we released a piece called "Snowballs Entering the Earth's Atmosphere?"
We were recently alerted that those snowballs may have been identified! Here's the scoop!
These snowballs may really be small comets. If the hypothesis is correct, these snowballs are millions of times smaller than comets like Halley's or Linear, but they are mainly made of water like these larger comets. They lack dust and iron though and so they do not glow or produce a bright tail.
These small comets may have been crashing into the Earth for the last 4.5 billion years! If that's true, then some or all of the Earth's water probably did come from these small comets.
It's been estimated that one small comet hits the Earth every three seconds. But, don't worry about getting hit by one of these snowballs! Small comets are not a danger to humans on Earth. They get torn apart at about 800 miles above the Earth and are vaporized by the Sun by about 600 miles above the Earth.
This may sound like something out of a cartoon show, but the Polar spacecraft may have confirmed the existence of these small comets originally found by Louis A. Frank of the University of Iowa. The Polar spacecraft sees the small comets from really far away. So, the next step is to send a spacecraft to see the small comets up close! That will help us to know whether or not this snowball hypothesis is correct!
Some scientists do not believe that Dr. Frank is actually seeing small comets. They do not believe the small comets hypothesis is correct. They think there is evidence that whatever Dr. Frank has discovered, it cannot be comets. Scientists are still debating whether the small comets hypothesis is true or not.
Shop Windows to the Universe Science Store!
Our online store
includes issues of NESTA's quarterly journal, The Earth Scientist
, full of classroom activities on different topics in Earth and space science, ranging from seismology
, rocks and minerals
, and Earth system science
You might also be interested in:
Scientists have been working for many years to try and figure out how the Earth first came to have water on it. Now there is a new theory -- the Small Comet theory. Dr. Louis Frank and Dr. John Sigwarth...more
Hale-Bopp continues to offer new surprises as two astronomers report of their study of the comet. Using the Hubble Space Telescope and the International Ultraviolet Explorer, the astronomers did a year-long...more
Six spacecraft flew by Halley's comet in 1986. There were two spacecraft launched from Japan, Suisei and Sakigake, and two from the Soviet Union, Vega 1 & 2. One spacecraft, ICE, from the United States...more
Comets are observed to go around the sun in a long period of time or a short period of time. Thus they are named "long-period" or "short-period" comets. One group of short-period comets, called the Jupiter...more
Scientists have learned a great deal from the crash of comet Shoemaker-Levy 9. Scientists traced the orbit of the comet backwards in time to guess its origin. The crash of a comet like Shoemaker-Levy 9...more
Mathematical theory suggests that comet Shoemaker-Levy 9 was likely a short-period comet which was captured into orbit around Jupiter in 1929 and began to execute the path plotted in this diagram. This...more
As the ices of the comet nucleus evaporate, they expand rapidly into a large cloud around the central part of the comet. This cloud, called the coma, is the atmosphere of the comet and can extend for millions...more