It was almost 11 o’clock in the morning on the 28th of September 1969 when above a
small rural town in south-eastern Australia a fireball was seen flying through the sky.
That fireball broke off into three parts and left behind a cloud of smoke. Half a minute
after that a tremor could be heard. This was when something called the Murchison meteorite
hit our fair planet. That rock broke off into lots of fragments, with one bit going right
through a roof and landing in some hay. The total weight of all the bits that were found
was about 220 pounds (100 kilograms). It became one of the most studied meteorites ever, and
one of the reasons why was that it contained lots of organic compounds. The question scientists
have been asking since then is did life on Earth come from outer space?
Some theories state that life on Earth started in something referred to as the primordial
soup. This soup contained organic molecules, and those include amino acids, which are the
building blocks of proteins. There are plenty of theories as to how life got there, but
scientists agree that the soup was left in the pan for many millions of years and eventually
complex life forms were created. We’ve done an entire show on why you exist at all, and
suffice to say it’s a complex matter. Today we’re going to concentrate only on meteorites
that might have carried life here. A meteorite is part of a meteor that breaks
off and doesn’t burn up before it gets to Earth. A comet is a chunk of ice and rock
that moves through space, often with a tail behind it. An asteroid is large piece of rock
that usually orbits between Mars and Jupiter but sometimes gets thrown off course. A meteor
is a rock that burns up and this is why they are sometimes called a shooting star or falling
star. Meteorites are the rocks that actually get here, hence we can look closely at them.
Researchers have for many years been looking closely at the one that hit Australia in many
pieces. In 2010, the Scientific American wrote about new research which revealed it contained
“millions of distinct organic compounds”, and that it was far more complex than first
thought. At the time, scientists were still trying to work out just what the meteorite
contained, since it was not straightforward. One researcher said, “It's exciting, but
it also scares me at the same time. We have a lot of work to do to even pretend to understand
what this stuff is.” A few years later and a planetary scientist
at the University of Chicago and a NASA astrophysicist got together to do an experiment. The Smithsonian
explained that those scientists created a computer model of the solar nebula. This is
the gaseous cloud from which it’s theorized our solar system was formed. That was way
back in 4.6 billion and a bit BC. Their debris in the model consisted of 5,000
icy grains moving about for millions of years. That’s simulation of course, not actually
millions of years. Within these grains were water, carbon dioxide, ammonia and other molecules.
Their computer model revealed that when irradiated by the sun in this experiment something profound
happened. The Smithsonian writes, “High-energy ultraviolet
radiation broke molecular bonds, creating highly reactive atoms that were prone to recombine
and form more stable—and sometimes, more complex—compounds.” The process could
have created organic compounds and with that proteins, RNA and DNA.
The theory those scientists came to was possibly that those organic compounds made their way
into the rocks in the early universe, some of which later got together to form planets,
such as the one you’re now sitting on. They might have also been part of other rocks such
as comets or meteorites that at some point made a splash in Earth’s primordial soup.
Scientists explain that because of Jupiter’s gravity some of those things called planetesimals
couldn’t join and form a proper planet. Planetesimals could be said to be very small
bodies of rock and dust, which measure over 1km in diameter. But Jupiter’s gravity forced
them to smash together and this formed a massive asteroid belt. From this asteroid belt smaller
rocks may have travelled to Earth. What’s interesting about this is that if
life on Earth did come from these rocks then they might have carried life to other planets
outside our solar system if the same conditions were present.
Now fast-forward to 2019 and listen to what some NASA scientists and some Japanese academics
had to say about what they found in two meteorites. They discovered something called ribose, which
is a sugar found in RNA and DNA. Why is this important? We’ll let one of the Japanese
researchers explain. He said: “The research provides the first
direct evidence of ribose in space and the delivery of the sugar to Earth. The extraterrestrial
sugar might have contributed to the formation of RNA on the prebiotic Earth which possibly
led to the origin of life.” They say possibly, nothing is certain just
yet. On NASA’s own website it states that the
discovery of ribose in a meteorite is just the latest of important compounds found in
those things, adding to the list of what we have already talked about. When big rocks
broke and then smaller ones hit Earth, they could have been carrying the essential ingredients
that would in the end make us. NASA explained that the messenger molecule,
RNA, copies genetic instructions from the thing we know as DNA. The point is to deliver
messages to cells that read the message and build proteins. That’s how things are made
in the life business. The researchers explained that the new discovery
gives a lot more credence to the theory of life not bubbling up through vents underwater
to reach the primordial swamp, but something that hit the swamp from space.
NASA wrote on its website: “Other important building blocks of life have been found in
meteorites previously, including amino acids (components of proteins) and nucleobases (components
of DNA and RNA), but sugars have been a missing piece among the major building blocks of life.”
So, maybe this was the missing part of the puzzle. Just some sugar was needed to make
conditions sweet enough for life to arise. More research needs to be done and other rocks
need to be studied. NASA was also quick to say that the sugars in the meteorites could
have come from down here. They might have been contaminated by life already here. The
agency, however, thinks that this is unlikely after analyzing the rocks.
It’s still up for debate, but the next video you need to watch definitely isn’t. Go watch
our incredible video “Astronomers Are Speechless After Spotting THIS Inside Black Hole” right
now for more insane space mysteries!