A publication made this Monday (18) on the official account of the James Webb Space Telescope (JWTS) on Like this. how’s that.
It was long believed that Jupiter’s powerful gravity helped deflect asteroids and comets away from Earth. However, little concrete evidence supports this theory, at least comfortingly.
Some studies suggest exactly the opposite, such as an article published in 2010 by Oxford University Press. Using computer simulations, astrophysicist Jonti Horner of the University of New South Wales, Australia, and Professor Barrie Jones of the Open University, UK, found that Jupiter actually increases the risk of a cosmic impact on Earth.
Simulations carried out by the researchers reveal that, although the gas giant does a good job of deflecting comets coming from well beyond our Solar System, it does the opposite with nearby comets and asteroids, putting them on a collision course with Earth and increasing the overall impact rate.
Early in Earth’s history, it is believed to have been struck by an object that had one to three times the mass of Mars – which would have formed our Moon. According to a 2009 newspaper article The New York TimesIf this impact did not occur, our world would likely be more like Venus, with surface temperatures unable to support liquid water and life.
Subsequently, a shower of comets and intense asteroid strikes would have hit the planet when it was young, releasing the volatile compounds necessary for the formation of the atmosphere, hydrosphere and biosphere.
Subsequently, however, the same types of impacts that brought life-forming elements to a young Earth could have annihilated it.
There have been five major mass extinction events in Earth’s history. While some opportunistic species thrived on the carnage, it took time for the biosphere to recover the diversity present before each of these catastrophic episodes.
One B612 Foundation study revealed that, between 2000 and 2013, our planet was hit by 26 objects exploding with a force between one and 600 kilotons (40 times the power of the Hiroshima bomb).
We can say that we are lucky, because if impact events were even larger and more frequent, the Earth’s biosphere would be totally different from what it is today – perhaps even non-existent.
Many, however, think that it has nothing to do with luck, defending the thesis that we owe it to Jupiter. It is widely believed that our giant neighbor acts as a cosmic shield, dramatically reducing the flow of planetesimals (rocky bodies from the beginning of the Solar System) between the planets closest to the Sun.
As popular as the idea of Jupiter as a “shield against comets” is, its origin is obscure. According to Horner and Jones “the idea that a giant planet beyond the orbit of a rocky planet is necessary to be habitable is well established in the astronomical community, but it is difficult to find the origin of Jupiter as a shield” .
This concept gained strength throughout the book Rare earth (Rare Earth), written by Peter Ward, geologist and evolutionary biologist, and Donald E. Brownlee, cosmologist and astrobiologist. In it, the authors state that “by clearing our Solar System of dangerous asteroids and comets that cross Earth’s orbit, Jupiter has a beneficial influence on life on our planet.”
The book, in turn, is based on a study by George Wetherill, who refers to Jupiter as something like “a barrier that must be penetrated by both Oort cloud comets and Kuiper belt asteroids if they are to achieve Earth-crossing orbits.” .”
However, the term “barrier” has a connotation in planetary dynamics that implies that Jupiter is more of a dynamic filter or membrane than an impenetrable shield.
In a subsequent paper published years later, Wetherill concluded that “rocky planetary systems most likely to resemble our own could be abundant but dangerous if not protected by gas giant planets.”
Taken out of context, this passage reads as if the author is advocating Jupiter’s function as a shield. However, according to the Arcadia space diarythe statement was actually made in reference to Jupiter’s role in ridding the outer Solar System of its last remaining planetesimals, drawing them inward, that is, toward the Earth’s periphery and nearby planets.
For the friendly Jupiter scenario, there appears to be a selection bias and only events in which it may have actually protected Earth are generally reported in the research. Cases in which the giant has put our planet in its cosmic sights, hurling asteroids and comets at us, have been largely ignored.
An example is comet C/1995 O1 Hale-Bopp. Based on orbital evidence shortly after the object was first observed in 1995, it appears to have made its final approach to the Sun 4,200 years ago, passing very close to Earth along the way. Computer models show that the comet was likely attracted by Jupiter a few weeks before the discovery, approaching Earth two years later, when it became known as the “Great Comet of 1997.”
There is an even more worrying example of Jupiter acting as an enemy of Earth. This is the case of comet D/1770L1 Lexell, whose passage near our planet in 1770 was the closest cometary near-miss recorded in history. It passed just over two million km from Earth (about five times the distance from here to the Moon).
Three years earlier, the same object had approached Jupiter, which had changed its path into a threatening orbit around the Earth. Lexell had another encounter with Jupiter in 1779, which completely ejected him from the Solar System.
With this comet, therefore, the gas giant acted first as a danger to the Earth and then as a protector.
The news that Jupiter could “hurl” comets and asteroids at Earth appeared first on Olhar Digital.
Source: Olhar Digital
Emma Smith is a thought-provoker and a writer at Run Down Bulletin. With a talent for crafting compelling arguments, she provides insightful and thought-provoking coverage of the most pressing opinion
