The Interior of Enceladus Looks Really Great for Supporting Life

When NASA’s Voyager spacecraft visited Saturn’s moon Enceladus, they found a body with young, reflective, icy surface features. Some parts of the surface were older and marked with craters, but the rest had clearly been resurfaced. It was clear evidence that Enceladus was geologically active. The moon is also close to Saturn’s E-ring, and scientists think Enceladus might be the source of the material in that ring, further indicating geological activity.

Since then, we’ve learned a lot more about the frigid moon. It almost certainly has a warm and salty subsurface ocean below its icy exterior, making it a prime target in the search for life. The Cassini spacecraft detected molecular hydrogen—a potential food source for microbes—in plumes coming from Enceladus’ subsurface ocean, and that energized the conversation around the moon’s potential to host life.

Now a new paper uses modelling to understand Enceladus’ chemistry better. The team of researchers behind it says that the subsurface ocean may contain a variety of chemicals that could support a diverse community of microbes.

Continue reading “The Interior of Enceladus Looks Really Great for Supporting Life”

Astronomers Report They’ve Detected the Amino Acid Glycine in the Atmosphere of Venus

Does it feel like all eyes are on Venus these days? The discovery of the potential biomarker phosphine in the planet’s upper atmosphere last month garnered a lot of attention, as it should. There’s still some uncertainty around what the phosphine discovery means, though.

Now a team of researchers claims they’ve discovered the amino acid glycine in Venus’ atmosphere.

Continue reading “Astronomers Report They’ve Detected the Amino Acid Glycine in the Atmosphere of Venus”

Did Pioneer See Phosphine in the Clouds of Venus Decades Ago?

The discovery of phosphine in Venus’ atmosphere has generated a lot of interest. It has the potential to be a biosignature, though since the discovery, some researchers have thrown cold water on that idea.

But it looks, at least, like the discovery is real, and that one of NASA’s Pioneer spacecraft detected the elusive gas back in 1978. And though it’s not necessarily a biosignature, the authors of a new study think that we need to rethink the chemistry of Venus’ atmosphere.

Continue reading “Did Pioneer See Phosphine in the Clouds of Venus Decades Ago?”

Maybe Volcanoes Could Explain the Phosphine in Venus’ Atmosphere

The detection of phosphine in Venus’ atmosphere was one of those quintessential moments in space science. It was an unexpected discovery, and when combined with our incomplete understanding of planetary science, and our wistful hopefulness around the discovery of life, the result was a potent mix that lit up internet headlines.

As always, some of the headlines were a bit of an over-reach. But that’s the way it goes.

At the heart of it all, there is compelling science. And the same, overarching question that keeps popping up: Are we alone?

Continue reading “Maybe Volcanoes Could Explain the Phosphine in Venus’ Atmosphere”

The Chemicals That Make Up Exploding Stars Could Help Explain Away Dark Energy

Astronomers have a dark energy problem. On the one hand, we’ve known for years that the universe is not just expanding, but accelerating. There seems to be a dark energy that drives cosmic expansion. On the other hand, when we measure cosmic expansion in different ways we get values that don’t quite agree. Some methods cluster around a higher value for dark energy, while other methods cluster around a lower one. On the gripping hand, something will need to give if we are to solve this mystery.

Continue reading “The Chemicals That Make Up Exploding Stars Could Help Explain Away Dark Energy”

Traces of One of the Oldest Stars in the Universe Found Inside Another Star

Despite all we know about the formation and evolution of the Universe, the very early days are still kind of mysterious. With our knowledge of physics we can shed some light on the nature of the earliest stars, even though they’re almost certainly long gone.

Now a new discovery is confirming what scientists think they know about the early Universe, by shedding light on a star that’s still shining.

Continue reading “Traces of One of the Oldest Stars in the Universe Found Inside Another Star”

The First Molecule that was Possible in the Universe has been Seen in Space

Image of planetary nebula NGC 7027 with illustration of helium hydride molecules. In this planetary nebula, SOFIA detected helium hydride, a combination of helium (red) and hydrogen (blue), which was the first type of molecule to ever form in the early universe. This is the first time helium hydride has been found in the modern universe. Credits: NASA/ESA/Hubble Processing: Judy Schmidt

It takes a rich and diverse set of complex molecules for things like stars, galaxies, planets and lifeforms like us to exist. But before humans and all the complex molecules we’re made of could exist, there had to be that first primordial molecule that started a long chain of chemical events that led to everything you see around you today.

Though it’s been long theorized to exist, the lack of observational evidence for that molecule was problematic for scientists. Now they’ve found it and those scientists can rest easy. Their predictive theory wins!

Continue reading “The First Molecule that was Possible in the Universe has been Seen in Space”

What are Molecules?


For millennia, scientists have pondered the mystery of life – namely, what goes into making it? According to most ancient cultures, life and all existence was made up of the basic elements of nature – i.e. Earth, Air, Wind, Water, and Fire. However, in time, many philosophers began to put forth the notion that all things were composed of tiny, indivisible things that could neither be created nor destroyed (i.e. particles).

However, this was a largely philosophical notion, and it was not until the emergence of atomic theory and modern chemistry that scientists began to postulate that particles, when taken in combination, produced the basic building blocks of all things. Molecules, they called them, taken from the Latin “moles” (which means “mass” or “barrier”). But used in the context of modern particle theory, the term refers to small units of mass.


By its classical definition, a molecule is the smallest particle of a substance that retains the chemical and physical properties of that substance. They are composed of two or more atoms, a group of like or different atoms held together by chemical forces.

Both simple and complex organic (carbon-containing) molecules have been found in space. Carbon is formed in the cores of red giant stars, where it gets cycled to the surface and dispensed into space. Credit: IAC; original image of the Helix Nebula (NASA, NOAO, ESA, the Hubble Helix Nebula Team, M. Meixner, STScI, & T.A. Rector, NRAO
Artist’s impression of simple and complex organic (carbon-containing) molecules that have been found in space. Credit: IAC/NASA/NOAO/ESA/Hubble Helix Nebula Team/M. Meixner/STScI/T.A. Rector/NRAO

It may consist of atoms of a single chemical element, as with oxygen (O2), or of different elements, as with water (H2O). As components of matter, molecules are common in organic substances (and therefore biochemistry) and are what allow for life-giving elements, like liquid water and breathable atmospheres.

Types of Bonds:

Molecules are held together by one of two types of bonds – covalent bonds or ionic bonds. A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. And the bond they form, which is the result of a stable balance of attractive and repulsive forces between atoms, is known as covalent bonding.

Ionic bonding, by contrast, is a type of chemical bond that involves the electrostatic attraction between oppositely charged ions. The ions involved in this kind of bond are atoms that have lost one or more electrons (called cations), and those that have gained one or more electrons (called anions). In contrast to covalence, this transfer is termed electrovalance.

In the simplest of forms, covelant bonds take place between a metal atom (as the cation) and a nonmetal atom (the anion), leading to compounds like Sodium Chloride (NaCl) or Iron Oxide (Fe²O³) – aka. salt and rust. However, more complex arrangements can be made too, such as ammonium (NH4+) or hydrocarbons like methane (CH4) and ethane (H³CCH³).

Diagram of a water molecule, which is made up of two hydrogen atoms and one oxygen atom. Credit:
Diagram of a water molecule, which is made up of two hydrogen atoms and one oxygen atom. Credit:

History of Study

Historically, molecular theory and atomic theory are intertwined. The first recorded mention of matter being made up of “discreet units” began in ancient India where practitioners of Jainism espoused the notion that all things were composed of small indivisible elements that combined to form more complex objects.

In ancient Greece, philosophers Leucippus and Democritus coined the term “atomos” when referring to the “smallest indivisible parts of matter”, from which we derive the modern term atom.

Then in 1661, naturalist Robert Boyle argued in a treatise on chemistry – titled “The Sceptical Chymist“- that matter was composed of various combinations of “corpuscules”, rather than earth, air, wind, water and fire. However. these observations were confined to the field of philosophy.

It was not until the late 18th and early 19th century when Antoine Lavoisier’s Law of Conservation of Mass and Dalton’s Law of Multiple Proportions brought atoms and molecules into the field of hard science. The former proposed that elements are basic substances that cannot be broken down further while the latter proposed that each element consists of a single, unique type, of atom and that these can join together to form chemical compounds.

Various atoms and molecules as depicted in John Dalton's A New System of Chemical Philosophy (1808). Credit: Public Domain
Various atoms and molecules as depicted in John Dalton’s A New System of Chemical Philosophy (1808). Credit: Public Domain

A further boon came in 1865 when Johann Josef Loschmidt measured the size of the molecules that make up air, thus giving a sense of scale to molecules. The invention of the Scanning Tunneling Microscope (STM) in 1981 allowed for atoms and molecules to be observed directly for the first time as well.

Today, our concept of molecules is being refined further thanks to ongoing research in the fields of quantum physics, organic chemistry and biochemistry. And when it comes to the search for life on other worlds, an understanding of what organic molecules need in order to emerge from the combination of chemical building blocks, is essential.

We have written many interesting articles about molecules for Universe Today. Here’s Molecules From Space May Have Affected Life On Earth, Prebiotic Molecules May Form in Exoplanet Atmospheres, Organic Molecules Found Outside our Solar System, ‘Ultimate’ Prebiotic Molecules Found in Interstellar Space.

For more information, check out Encyclopaedia Britannica‘s page on molecules.

We’ve also recorded an entire episode of Astronomy Cast all about Molecules in Space. Listen here, Episode 116: Molecules in Space.