The Asteroid Belt

• Asteroids: These are big rocks that circle the Sun.

• Asteroid Belt: The vast majority of asteroids are safely beyond the orbit of Mars in an area.

• Asteroids range in size from Ceres, which is 587 miles across, and are merely asteroidal fragments.

• Asteroidal meteoroids: These are made of rock and/or iron; when they fall to Earth, they’re called meteorites.

• Jupiter Trojans: Asteroids that are trapped in Jupiter’s orbit around the sun.

• The “Big Four” of the Asteroid Belt:

  • Ceres

  • Pallas

  • Vesta

  • Hyglea

Vesta and Ceres Highlights (by Dawn)

• The southern polar region of Vesta is dominated by two enormous impact basins; the larger one, Rheasilvia, is 310 miles wide and about 12 miles deep, with a central peak higher than the Mauna Kea volcano in Hawaii.

• Vesta does not have any volcanic features of any kind, but Dawn did find surface minerals similar to those found in basaltic lava flows on Earth.

• Vesta may be a surviving example of a protoplanet, which is a stage in the formation of a planet that is just before the formation of a planet.

• Ahuna Mons, a mountain on Ceres 11 miles wide ad 2.5 miles high, is a cryovolcano.

  • It is a geological structure that brought mineral-rich water from deep within Ceres to the surface, where it froze and deposited the minerals that make up the mountain.

• Unusual bright white spots appear on the floor of Ceres’ Occator crater.

Threat That Near-Earth Objects Pose

• Thousands of small asteroids have orbits that cross or approach Earth's orbit. Near-Earth objects (NEOs) are what astronomers refer to as these neighbors, and as of February 2017, 1,773 of them had been identified as potentially hazardous asteroids (PHAs).

• The Minor Planet Center (MPC) of the International Astronomical Union keeps tabs on PHAs, and several observatories sweep the skies to discover more of them.

• There isn't currently a known object that poses a threat to Earth, according to astronomers.

• A few-mile-long rock striking the planet at 25,000 miles per hour would be far more catastrophic than the simultaneous detonation of all known nuclear weapons.

• Chicxulub crater: The 110-mile-wide geologic feature, which lies partially on Mexico's Yucatan peninsula and partially offshore in the Gulf of Mexico, may be the last remaining sign of the impact that is thought to have wiped out the dinosaurs.

• An impact by a small asteroid caused the famous Meteor Crater in northern Arizona, near Flagstaff.

  • It is the largest and best-preserved impact crater on Earth, making the location well worth a trip.

• Gravity Tractor: A massive spacecraft would fly along with the asteroid for a period of years.

Occultation

• Occultation: A kind of eclipse that occurs when a moving body in the solar system passes in front of a star.

  • It can occasionally show that a star that appears to be common is actually a close binary system.

  • Binary System: Two stars in orbit around a common center of mass.

• Occultation Ground Track: An area of the Earth's surface that is expected to be visible for the occultation, similar to the path of totality during a solar eclipse.

• International Occultation and Timing Association (IOTA): They tell all you want to know about observing occultations.

• You must time your asteroidal observation precisely and be aware of your exact location at the time of the occultation in order for it to be scientifically useful.