A view of the Earth from space. What shape does it look like to you?
Click on image for full size
Image courtesy of NASA/JPL

The Equator is Growing!
News story originally written on August 7, 2002

Earth may look perfectly spherical from space, like a giant marble, but it actually isn't! Since the first satellites were launched, scientists realized that Earth is not a sphere. Instead, our planet is wider around the equator because matter is forced out as Earth spins (just as you feel you are pushed right when your car turns fast to the left). However, Earth doesn't stay the same, and scientists have been tracking some interesting changes in our planet's shape.

Standing on Earth's surface can not see the small changes in Earth's shape but researchers have been watching the equator shrink slowly over the past few decades with satellites, a process that they believe has been going on since the last ice age 18,000 years ago. Since the ice age, glaciers at the poles have been melting slowly as global temperatures warm, allowing magma under Earth's crust to move towards the poles once the heavy weight of ice was no longer squashing them. This allowed the equator to shrink as the molten rock (magma) moved away.

For the past four years, however, Earth has been doing something quite different. Researchers at Raytheon and NASA's Goddard Space Flight Center have been watching the equator grow larger. Since we know that glaciers are still melting at the poles, scientists are puzzled why the process would change.

For Earth's equator to increase in size, material must have been moved from somewhere else on the planet. One hypothesis is that molten rock has been moving within the Earth to below the equator. This may have been caused by the brief reversal of the Earth's magnetic field that occurred in 1999, which happens about once every 10 years. One of these reversals may have caused changes in the circulation of magma in the Earth's interior.

Another hypothesis is that there is more ocean water piling up at the equator. As the polar ice caps melt, they add more water into the oceans, which will move with the ocean currents towards the equator.

Whatever the reason, the researchers believe that this change in the shape of Earth is the result of long-term natural variations, and is not anything that humans have done to the planet.

You might also be interested in:

Cool It! Game

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

The Earth's Magnetosphere

The Earth has a magnetic field with north and south poles. The magnetic field of the Earth is enclosed in a region surrounding the Earth called the magnetosphere. As the Earth rotates, its hot core generates...more

1999--A Year in Review...

It was another exciting and frustrating year for the space science program. It seemed that every step forward led to one backwards. Either way, NASA led the way to a great century of discovery. Unfortunately,...more

STS-95 Launch: "Let the wings of Discovery lift us on to the future."

The Space Shuttle Discovery lifted off from Kennedy Space Center at 2:19 p.m. EST, October 29th. The sky was clear and the weather was great as Discovery took 8 1/2 minutes to reach orbit for the Unitied...more

Moon Found Orbiting Asteroid

A moon was discovered orbiting the asteroid, Eugenia. This is only the second time in history that a satellite has been seen circling an asteroid. A special mirror allowed scientists to find the moon...more

U.S. is Fed Up with Russia

Will Russia ever put the service module for the International Space Station in space? NASA officials are demanding an answer from the Russian government. The necessary service module is currently waiting...more

More on Recent Coronal Mass Ejection

During a period of about two days in early May, 1998, the ACE spacecraft was immersed in plasma associated with a coronal mass ejection (CME). The SWICS instrument on ACE, which determines unambiguously...more

Mother Nature's Air Conditioning

J.S. Maini of the Canadian Forest Service has referred to forests as the "heart and lungs of the world." Forests reduce soil erosion, maintain water quality, contribute to atmospheric humidity and cloud...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