Theia is a hypothesized ancient planet in the early Solar System that, according to the giant-impact hypothesis, collided with the early Earth around 4.5 billion years ago, with some of the resulting ejected debris gathering to form the Moon.
NASA knows of no asteroid or comet currently on a collision course with Earth, so the probability of a major collision is quite small. In fact, as best as we can tell, no large object is likely to strike the Earth any time in the next several hundred years.
Scientists Find Strong Evidence That the Earth Was Hit Head-On by a Mars-Sized Planet. A new analysis of lunar rock and soil samples suggests that the Earth got full-on clobbered by an ancient planet called Theia. The early solar system was, for lack of a better term, a chaotic hellscape.
So then, with the scant evidence we have, what would theoretical Theia have looked like? Like most newborn planets, she was probably a seething mass of rock, about the size of Mars, ricocheting through the early inner solar system.
Theia is hypothesized to have been about the size of Mars, and may have formed in the outer Solar System and provided much of Earth's water.
Pieces of the planet may also exist in the moon.
A new study led by Qian Yuan, a geodynamics researcher at Arizona State University (ASU), Tempe, suggests that the remnants of Theia is still inside Earth, probably located in two continent-size layers of rock beneath West Africa and the Pacific Ocean.
The European Space Agency maintains a risk list of 1,460 objects, which catalogs every object with a non-zero chance of hitting Earth over the next 100 years. Asteroid 2023 DZ2, which is in orbit around the sun, is not on the risk list.
NASA scientists say it would take an asteroid 60 miles (96 kilometers) wide to totally wipe out life on Earth. Asteroid Didymos (bottom left) and its moonlet, Dimorphos are seen less than three minutes before NASA's DART spacecraft made impact.
Evidence suggests an asteroid impact was the main culprit. Volcanic eruptions that caused large-scale climate change may also have been involved, together with more gradual changes to Earth's climate that happened over millions of years.
In fact, currently, there are no large asteroids predicted to hit Earth for the next 100 years. The object with the highest probability of colliding with Earth was the 1,100 feet (340 m) wide asteroid 99942 Apophis, which was predicted to get dangerously close to Earth in 2068.
Such an impact would kill all life on our planet. Nothing would survive. By contrast, the asteroid that doomed the dinosaurs 65 million years ago was likely just 6 miles in diameter; Mercury is 3,032 miles across. The last time an object about that size hit the Earth, the resulting debris formed our Moon.
When the 6-mile-wide asteroid that led to dinosaur extinction hit Earth 66 million years ago, the impact also triggered a “mega-earthquake” that lasted weeks to months, new evidence suggests.
Based on crater formation rates determined from the Earth's closest celestial partner, the Moon, astrogeologists have determined that during the last 600 million years, the Earth has been struck by 60 objects of a diameter of 5 km (3 mi) or more.
Washington, DC—Our planet's water could have originated from interactions between the hydrogen-rich atmospheres and magma oceans of the planetary embryos that comprised Earth's formative years, according to new work from Carnegie Science's Anat Shahar and UCLA's Edward Young and Hilke Schlichting.
Although Earth doesn't have a ring system today, it may have had one in the past. All gas giant planets (Jupiter, Saturn, Uranus and Neptune) in the Solar System have rings, while the terrestrial ones (Mercury, Venus, Earth and Mars) do not. There are two theories about how ring systems develop.
Scientists have predicted that Earth will get warmer by the year 2027 compared to the 19th century and this may change the weather conditions of the world.
An asteroid, named "2019 PDC", was discovered that will come dangerously close to the earth 8 years from now, on April 29, 2027. The space rock is between 330 and 1000 feet in size, somewhere in between the length of 6.5 school buses to the height of two Washington Monuments stacked on top of each other.
“This is what we call a planet killer,” astronomer Scott Sheppard told the New York Times last year after scientists found a new 1.5-kilometer asteroid. “If this one hits the Earth, it would cause planet-wide destruction. It would be very bad for life as we know it.”
Montage of our solar system. Asteroid 1997 XF11 will pass well beyond the Moon's distance from Earth in October 2028 with a zero probability of impacting the planet, according to astronomers at NASA's Jet Propulsion Laboratory, Pasadena, CA.
Orbit and Rotation
As a result of its close encounter with Earth in 2029, the asteroid's orbit will be widened to become slightly larger than the width of Earth's orbit. At this point, it will be reclassified from the Aten group to the "Apollo" group (the group of Earth-crossing asteroids with orbits wider than 1 AU).
Earth once had two moons, which merged in a slow-motion collision that took several hours to complete, researchers propose in Nature today. Both satellites would have formed from debris that was ejected when a Mars-size protoplanet smacked into Earth late in its formation period.
Venus and Earth are sometimes called twins because they're pretty much about the same size. Venus is almost as big as Earth. They also formed in the same inner part of the solar system. Venus is in fact our closest neighbor to Earth.
Using data from NASA's Transiting Exoplanet Survey Satellite, scientists have identified an Earth-size world, called TOI 700 e, orbiting within the habitable zone of its star – the range of distances where liquid water could occur on a planet's surface.