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 wrote that snowballs from space may be hitting the Earth!
We were recently alerted that those snowballs may have been identified! Here's the scoop!
These snowballs may be really small comets. They are millions of times smaller than comets like Halley's or Linear.
Scientists think that the comets are made mostly of water...that's why they were originally called snowballs! But, don't worry about getting hit by one of these snowballs! Even though one small comet probably hits the Earth's atmosphere every three seconds, they are not dangerous to humans or animals, because they break up in the atmosphere.
Scientists want to take measurements from close-up. 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! (Remember, theories have to be proven over and over again for them to be considered true!)
Some scientists do not believe in the small comets hypothesis. They think that there must be some other explanation of the data. Scientists are still having a debate about the small comets idea. Some say it is true, but others think it is false. We still don't know for sure!
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, as well as books
on science education!
You might also be interested in:
There are small snow comets that crash into the Earth's atmosphere. About 20 snow comets weighing 20 to 40 tons each crash into the Earth's atmosphere every minute! Scientists have seen these small comets...more
Comet Hale-Bopp was one of the brightest comets of all time. Astronomers witnessed the comet spew out intermittent bursts of dust. The surface seemed to be an incredibly dynamic place, with 'vents' being...more
Six spacecraft flew to Halley's comet in 1986. There were two spacecraft launched from Japan, named Suisei and Sakigake, and two from the Soviet Union, named Vega 1 & 2. One spacecraft, ICE, was from the...more
Astronomers have noticed a group of comets which they call the Jupiter Family of Comets. This family of comets is to be found circling between Jupiter and the sun, as shown in this picture. The comets...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. This orbit ended with a collision of the comet with Jupiter...more
As the ices of the comet nucleus evaporate, they expand into a large cloud around the middle part of the comet. This cloud, called the coma, is the atmosphere of the comet. It can extend for millions of...more