Space
Life in the solar system may have first originated on Mars, not Earth
A new study published in the journal Science Advances suggests that the organic molecules that allowed life to begin were present on Mars about 4.5 billion years ago.
And while these critical components may have hit Earth around the same time, it was on the Red Planet that life found its most favorable conditions.
Earth and Mars are members of the inner solar system, made up of four rocky planets and an asteroid belt. Shortly after their formation, these terrestrial planets were brutally bombarded when a shower of asteroids hit the inner solar system.
While these rocks were assimilated into the crust of Earth and Mars, the movement of plate tectonics on our home world caused these ancient meteors to fall into the interior of the planet.
In contrast, the surface of Mars is stationary, meaning that rocks that crashed into the planet in the distant past remain in place and can be studied.
By analyzing 31 Martian meteorites, the authors of the study sought to answer a number of fundamental questions about their origin.
For example, until now, scientists have not determined where these ancient projectiles from the inner or outer solar system came from, and whether they carried any organic material that could allow life to develop.
Using ultra-precise measurements of chromium isotopes, the researchers identified the meteorites as carbonaceous chondrites from the outer solar system.
Based on the prevalence of such rocks on Mars and the fact that ice typically makes up 10 percent of their mass, the authors calculated that these ancient impacts brought enough water to Mars to cover the entire planet in 307 meters of water.
Remarkably, carbonaceous chondrites from the outer solar system also transported organic molecules such as amino acids to the inner solar system.
These compounds are essential for the formation of DNA and likely provided the raw materials that allowed life to begin.
“At this time, Mars was bombarded with ice-filled asteroids. This happened in the first 100 million years of the evolution of the planet ,” study author Professor Martin Bizzarro explained in a statement. “Another interesting aspect is that the asteroids also carried organic molecules that are biologically important to life.”
However, while conditions on Mars may have been ideal for life at this early stage, the same cannot be said for Earth. “After that period, something catastrophic happened to potential life on Earth, ” says Bizzaro.
It is believed that a giant collision has taken place between Earth and another planet the size of Mars. It was an energetic collision that formed the Earth-Moon system and at the same time destroyed all potential life on Earth.
Taken together, these results indicate that life likely had a better chance of thriving on Mars than on Earth during the formative years of the inner solar system.
In a study published in the Astrophysical Journal, astrophysicists set out to find out if exoplanets could support life.
Astronomers have come to the conclusion that on the surface of some exoplanets there is a strip that may contain water, necessary for the existence of biological life. The terminator zone is the dividing line between the day and night sides of an exoplanet.
Many exoplanets are planets outside the solar system held by gravity. This means that one side of the planet is always facing the star they orbit, while the other side is in constant darkness.
The water on the dark side will most likely be in a frozen state, while on the light side it will be so hot that the water should just evaporate.
The terminator zone would be a “friendly place” – neither too hot nor too cold – in which liquid water could support extraterrestrial life.
Dr. Ana Lobo of the University of California, said: “The day side can be scalding hot, much uninhabitable, while the night side will be icy, potentially covered in ice. You need a planet that’s the right temperature for liquid water.”
“We’re trying to draw attention to planets with more limited amounts of water that, despite not having widespread oceans, might have lakes or other smaller bodies of liquid water, and that climate could actually be very promising.”
“By exploring these exotic climate states, we are improving our chances of finding and correctly identifying a habitable planet in the near future.”
The researchers created a model of their climate by analyzing different temperatures, wind patterns and radiative forcing, and found the “correct” zone on exoplanets that could contain life-supporting liquid water.
Researchers who are looking for life on exoplanets will now take into account the fact that it can hide in certain areas.
The notion of the Big Bang goes back nearly 100 years, when the first evidence for the expanding Universe appeared.
If the Universe is expanding and cooling today, that implies a past that was smaller, denser, and hotter. In our imaginations, we can extrapolate back to arbitrarily small sizes, high densities, and hot temperatures: all the way to a singularity, where all of the Universe’s matter and energy was condensed in a single point.
For many decades, these two notions of the Big Bang — of the hot dense state that describes the early Universe and the initial singularity — were inseparable.
But beginning in the 1970s, scientists started identifying some puzzles surrounding the Big Bang, noting several properties of the Universe that weren’t explainable within the context of these two notions simultaneously.
When cosmic inflation was first put forth and developed in the early 1980s, it separated the two definitions of the Big Bang, proposing that the early hot, dense state never achieved these singular conditions, but rather that a new, inflationary state preceded it.
There really was a Universe before the hot Big Bang, and some very strong evidence from the 21st century truly proves that it’s so.
Although we’re certain that we can describe the very early Universe as being hot, dense, rapidly expanding, and full of matter-and-radiation — i.e., by the hot Big Bang — the question of whether that was truly the beginning of the Universe or not is one that can be answered with evidence.
The differences between a Universe that began with a hot Big Bang and a Universe that had an inflationary phase that precedes and sets up the hot Big Bang are subtle, but tremendously important. After all, if we want to know what the very beginning of the Universe was, we need to look for evidence from the Universe itself.
Read the full article here.
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