Travel the universe with Dr. Ethan Siegel as he answers the biggest questions of all
It’s not just for Earth-like planets around Sun-like stars. Not even close.
Shortly after Earth first formed first formed, life quickly took hold, thriving ever since.
Both reflected sunlight on a planet and absorbed sunlight filtered through an atmosphere are two techniques humanity is presently developing to measure the atmospheric content and surface properties of distant worlds, including worlds that may be similar to an early version of Earth. In the future, this could include the search for organic signatures as well. (MELMAK / PIXABAY)
Perhaps terrestrial life didn’t originate here, but arrived from elsewhere through natural processes.
Organic molecules are found in star forming regions, stellar remnants and interstellar gas, all throughout the Milky Way. In principle, the ingredients for rocky planets and life on them could have come about quite quickly in our Universe, long before Earth ever existed. (NASA / ESA AND R. HUMPHREYS (UNIVERSITY OF MINNESOTA))
Surprisingly, the raw ingredients necessary for life exist almost everywhere astronomers look.
Signatures of organic, life-giving molecules are found all over the cosmos, including in the largest, nearby star-forming region: the Orion Nebula. Someday soon, we may be able to look for biosignatures in the atmospheres of Earth-sized worlds around other stars, or we may detect simple life directly on another world in our Solar System. (ESA, HEXOS AND THE HIFI CONSORTIUM; E. BERGIN)
Here are 10 locations where they’re ubiquitous.
Ultra-hot, young stars can sometimes form jets, like this Herbig-Haro object in the Orion Nebula, just 1,500 light years away from our position in the galaxy. The radiation and winds from young, massive stars can impart enormous kicks to the surrounding matter, where we find organic molecules as well. (ESA / HUBBLE & NASA, D. PADGETT (GSFC), T. MEGEATH (UNIVERSITY OF TOLEDO), AND B. REIPURTH (UNIVERSITY OF HAWAII))
1.) Jets emitted from newly forming stars, Herbig Haro objects, contain all sorts of organic molecules.
The protoplanetary disk around the young star, HL Tauri, as photographed by ALMA. The gaps in the disk indicate the presence of new planets, while spectroscopic measurements reveal a large number and diversity of organic, carbon-containing compounds. (ALMA (ESO/NAOJ/NRAO))
Pluto’s atmosphere, as imaged by New Horizons when it flew into the distant world’s eclipse shadow. The atmospheric hazes are clearly visible, and are measured to contain a number of organic, carbon-containing compounds. (NASA / JHUAPL / NEW HORIZONS / LORRI)
3.)Pluto, the largest world in our Kuiper belt, contains tholins, methane, and organic-rich hazes.
The Iris Nebula, also known as NGC 7023, is a reflection nebula well-known for containing a large variety of complex and organic molecules. Reflection nebulae are a common locale for the raw ingredients for life. (GÖRAN NILSSON / HOLE OBSERVATORY)
Scores of amino acids not found in nature are found in the Murchison Meteorite, which fell to Earth in Australia in the 20th century. The fact that 80+ unique types of amino acids exist in just a plain old space rock might indicate that the ingredients for life, or even life itself, might have formed differently elsewhere in the Universe, perhaps even on a planet that didn’t have a parent star at all. (WIKIMEDIA COMMONS USER BASILICOFRESCO)
5.) Inside meteorites, amino acids and proteins abound, including ones not naturally occurring on Earth.
A multiwavelength view of the galactic center shows stars, gas, radiation and black holes, among other sources. There is a tremendous amount of material there, including the heavy elements and organic compounds that are the necessary precursors to life. Ethyl formate, the molecule that gives raspberries and rum their unique scent, is found here. (NASA/ESA/SSC/CXC/STSCI)
6.) The galactic center’s gas includes ethyl formate: the compound responsible for raspberries’ unmistakable scent.
A small portion of the Taurus Molecular Cloud, as constructed from several observations from ESA’s Herschel space observatory. The brighter, red-hued regions have the highest density and active star formation, while the blue-hued areas correspond to colder, less dense portions. Organic molecules are found throughout. (ESA/HERSCHEL/NASA/JPL-CALTECH; ACKNOWLEDGEMENT: R. HURT (JPL-CALTECH),CC BY-SA 3.0 IGO)
Nitrogen, hydrogen and oxygen are highlighted in the planetary nebula above, known as the Hourglass Nebula for its distinctive shape. The assigned colors distinctly show the locations of the various elements, which are segregated from one another. Complex molecules, including fullerenes containing 60 carbon atoms apiece, have been found in various planetary nebulae (and other locations) in space. (NASA/HST/WFPC2; R SAHAI AND J TRAUGER (JPL))
8.) Planetary nebulae, created when sun-like stars die, contain over 20 molecular species, including fullerenes.
Colloquially known as galactic cirrus clouds, these dark nebulae are actually clouds of molecular gas found in the disk and halo of the Milky Way. They contain over 100 organic molecules between them, many of which could serve as the precursors to life. (JOSÉ JIMÉNEZ / ASTROMET / FLICKR)
NASA’s Curiosity rover has discovered ancient organic molecules on Mars, embedded within sedimentary rocks that are billions of years old. These contain carbon and sulfur, and may be connected to life beyond Earth. (NASA/GSFC)
Cape St. Vincent, shown here in assigned color, is one of many such capes around the rim of Victoria crater. The stratified layers of ground provide evidence for a sedimentary rock history on Mars, which also implies the past presence of liquid water. Opportunity’s discovery of the mineral jarosite was a game-changer for Martian geology, and could even be an indicator of past (or even present) life on the red planet. (NASA / JPL / CORNELL)
The ingredients for life are practically everywhere. Perhaps life is, too.
First proposed many decades ago, the idea that Earth’s life originated prior to Earth has become known as panspermia. Although this possibility was once derided, a plethora of recent discoveries has compelled us to take the idea seriously. Perhaps life on Earth had an origin that occurred off-world, and perhaps the precursor ingredients found elsewhere will give rise to life on other worlds as well. (GETTY)
Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words. Talk less; smile more.
