Shop Windows to the Universe

Earth Science Rocks! Select one of our four cool NESTA t-shirts from our online store, and express your love of Earth and space science!
This is a drawing of what the surface of a comet might look like.
Click on image for full size
JPL

The Comet Nucleus

The nucleus of a comet is the central portion of the head of a comet. It is a solid part of the comet, made of a special sort of dust which is called "fluffy" because it could be as light weight and full of holes as a sponge. The holes of this "sponge" are filled with ices like water, carbon dioxide (dry ice), and carbon monoxide (what comes out of your car).

Observations of the nuclei of comet Hale-Bopp and Hyakutake have given scientists fresh ideas about comet composition and evolution. But, scientists still don't know whether the nucleus is very hard, like solid ground, or very soft and breakable, like a snowball. The Rosetta mission hopes to land a probe on the surface of a comet to find out just how hard it is!

As a comet approaches the Sun, it begins to evaporate, forming the coma and a spectacular comet tail. This picture shows that evaporation may happen only in specific places on the nucleus. These spots of evaporation are called "jets". Halley's comet had three distinct jets on its surface as it approached the Sun in 1986.

Last modified June 22, 2005 by Jennifer Bergman.

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, oceanography, and Earth system science to astronomy!

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Brownlee Particles

This example of Interstellar Dust is a perfect example of the kind of rocky material that may make comets. The grains themselves seem to be made of smaller grains. There are many holes, or pores. In a...more

Comet Hale-Bopp

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

When a Comet comes close to the Sun

When comets are kicked out of the Oort Cloud, they begin a passage into the solar system, spinning and tumbling as they come. The trajectory which they acquire can be hyperbolic, parabolic, or elliptic...more

The Comet Coma

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

Nucleus of Comet Wild 2

The picture on this page shows the best views ever of the nucleus of a comet. It shows two pictures of the comet's nucleus that were taken at slightly different times. The pictures were taken by a spacecraft...more

CONTOUR on its Way to Catch a Comet!

NASA’s Comet Nucleus Tour (CONTOUR), launched July 3, 2002. The CONTOUR spacecraft will fly by at least two comets, taking pictures and collecting dust from the nucleus of each comet to help scientists...more

CONTOUR Lost in Space

We are sad to report that the Comet Nucleus Tour (CONTOUR) is currently lost in space. The CONTOUR spacecraft was launched July 3, 2002 to explore the nucleus of comets. It was scheduled to fly by at...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA