Clues of Life's Origins Found in Galactic Cloud
You and I are both made up of an eclectic collection of organic molecules.
A lot of interesting molecules go into making up all life on Earth, from the amino acids which make up proteins to the nucleobases that encode our very DNA, but where they exactly come from (on a cosmic scale) is still one of science’s great mysteries. And as with any good mystery, the only solution will be to solve each of the separate pieces of the puzzle — and the latest piece of this puzzle has just been spotted in a huge gas cloud in the center of our galaxy.
Finding things like amino acids in space directly is a difficult business. So, instead of finding them directly, a team using West Virginia’s Green Bank Telescope, led by Anthony Remijan, discovered two other molecules – cyanomethanimine and ethanamine — both of which are precursor molecules. In other words, these molecules are the early steps in the chain of chemical reactions that go on to make the stuff of life.
Astrochemists are steadily discovering larger and more complex molecules in interstellar space. Recent years have seen the discoveries of glycolaldehyde, which is arguably the simplest type of sugar, and ethyl formate, one of the molecules responsible for the flavor and aroma of rum and raspberries. This latest discovery might not sound quite as appetizing, but it’s no less important.
When hunting for new molecules, astrochemists frequently turn their telescopes towards the galactic center. Drifting in the Milky Way’s core, is a hulking interstellar cloud known as Sagittarius B2 (or Sgr B2 for short). Spanning 150 light-years in size, Sgr B2 is one of the galaxy’s largest clouds, up to 40 times as dense as any other the Milky Way has to offer.
Sgr B2 is also something of a benchmark for molecule hunters. Roughly 25,000 light-years from Earth, and only about 390 light years from the supermassive black hole lurking in the galactic center, if any molecule can be found in the interstellar medium, it can be found here.
The two molecules that Remijan and his team found, cyanomethanimine and ethanamine, are expected to be precursors to the nucleobase adenine and the amino acid alanine, respectively. This makes them potentially very important discoveries. It’s expected that molecules like this form, and continue to react, on the surfaces of interstellar ice grains. These ice grains condense like hailstones in the freezing conditions of interstellar clouds. Once formed, some molecules escape into the vacuum of space, while others react further — forming increasingly complex molecules.
Remijan noted that, ”Finding these molecules in an interstellar gas cloud means that important building blocks for DNA and amino acids can ‘seed’ newly-formed planets with the chemical precursors for life.” Logical, because the vast interstellar clouds where these molecules are formed are the very same clouds that go on to collapse into stars and planets.
Extraterrestrial amino acids and DNA nucleobases like adenine have been found in meteorites, suggesting that there must be mechanisms occurring in space that create them. If they can be created in space, it’s likely that they can also been seen using telescopes. All we need to do is make sure our telescopes are sensitive enough, look in the right places, and make sure we know what it is we’re looking for.
Hopefully, if astrochemists keep looking for complex molecules like these, we’ll eventually be able to answer some of the biggest questions out there — such as the question of how life first started on our planet, how it might happen on other planets, and whether or not we’re alone in the galaxy.
Image: The reflection nebula IRAS 10082-5647, illuminated by a young star. Places like this could be where complex molecules are formed and incorporated into newly forming star systems. Credit: ESA/Hubble & NASA