Meteorite bombardment and dating of planetary surfaces show

meteorite bombardment and dating of planetary surfaces show

The The First Billion Years: Bombardment conference will be held September October 3, in Flagstaff, Arizona. Meeting Location and Dates This topical conference on Bombardment, the third in The First Billion Years series, Mars, the asteroid belt, outer solar system moons, and planetary systems elsewhere. Melt rocks returned from the Moon date to a narrow interval of lunar bombardment There is now evidence to show that this so-called Late Heavy Bombardment to a set of calculations, random asteroid impacts may have aided the planet's in size and composition, but different in surface and interior characteristics. Dating by measurement of impact crater frequencies developed in the past years primarily on the basis of the data from the missions to the Moon and Mars.

New Insight into Earth’s Early Bombardment

Researchers examined about 50 different melted rock samples collected by astronauts during the Apollo missions in the late s and s. Using radiometric dating techniques, they found that all but a few of the rocks were between 3.

Earth itself is about 4. Furthermore, many of the samples displayed different chemical "fingerprints," which suggests that they were formed from different meteorites and lunar rocks.

meteorite bombardment and dating of planetary surfaces show

Meteorites affected Earth as well All you have to do is look at the Moon to see that it has been hit hard. All the craters are a record of past impacts, and unless obliterated by a subsequent larger impact, the craters remain relatively intact because the Moon has no air to weather them and little internal activity like the volcanoes and earthquakes that constantly remake our planet.

Venus: Death of a Planet

Any meteorite activity that affected the Moon probably affected Earth as well, scientists say. But terrestrial evidence for the LHB is scarce. Inhowever researchers discovered in sedimentary rocks a version of the element tungsten in amounts not normally found on Earth.

meteorite bombardment and dating of planetary surfaces show

The tungsten is believed to be of extraterrestrial origin and was estimated to about 3. Implications for life If the pockmarked surface of the Moon is any indication, early Earth was pelted by a fairly steady stream of meteorites--some as big as 6 miles or more across--for about million years.

Any life that was present or developing on Earth at the time would have been in constant peril of being blasted out of existence.

meteorite bombardment and dating of planetary surfaces show

Planet V hypothesis[ edit ] Main article: Planet V The Planet V hypothesis posits that a fifth terrestrial planet created the Late Heavy Bombardment when its meta-stable orbit entered the inner asteroid belt.

The hypothetical fifth terrestrial planet, Planet V, had a mass less than half of Mars and originally orbited between Mars and the asteroid belt. Planet V's orbit became unstable due to perturbations from the other inner planets causing it to intersect the inner asteroid belt.

meteorite bombardment and dating of planetary surfaces show

After close encounters with Planet V, many asteroids entered Earth-crossing orbits producing the Late Heavy Bombardment. Planet V was ultimately lost, likely plunging into the Sun.

In numerical simulations, an uneven distribution of asteroids, with the asteroids heavily concentrated toward the inner asteroid belt, has been shown to be necessary to produce the LHB via this mechanism. This Vesta -sized asteroid was a remnant of a population which initially was much larger than the current main asteroid belt. Most of the pre-Imbrium impacts would have been due to these Mars-crossing objects, with the early bombardment extending until 4.

New Insight into Earth’s Early Bombardment

A lull in basin-forming impacts then followed during which the lunar magnetic field decayed. Many of these objects then evolved onto Earth-crossing orbits producing a spike in the lunar impact rate during which the last few lunar impact basins are formed. Other potential sources[ edit ] A number of other possible sources of the Late Heavy Bombardment have been investigated.