substance

nitrogen

A chemical element with atomic number 7, making up most of Earth's atmosphere.
24 related articles

Description

Nitrogen is a chemical element with atomic number 7, making up about 78% of Earth's atmosphere. It is a colorless, odorless, and largely inert gas at standard conditions, but it plays a crucial role in planetary atmospheres, astrophysical chemistry, and the search for life beyond Earth. In planetary science, nitrogen is a key volatile element that helps scientists understand atmospheric evolution, loss processes, and the potential habitability of exoplanets.

History

Nitrogen was discovered in 1772 by Scottish physician Daniel Rutherford, who isolated it as a gas that did not support combustion or life. The name comes from the Greek 'nitron' (saltpeter) and 'genes' (forming), reflecting its presence in nitric acid and nitrates.

How it works

Nitrogen exists primarily as molecular N₂, a very stable molecule held together by a strong triple bond. This stability makes it chemically inert at low temperatures, but under high pressure or in the presence of energetic processes (such as lightning or stellar radiation), it can form reactive compounds like ammonia (NH₃) or nitrogen oxides. In planetary atmospheres, nitrogen can be lost to space through thermal escape or sputtering, and its isotopic ratios (e.g., ¹⁴N/¹⁵N) provide clues about atmospheric history and sources.

In practice

Nitrogen is used in cryogenics (liquid nitrogen for cooling), food preservation (inert packaging), and as a key component in fertilizers (ammonia synthesis via the Haber-Bosch process). In astrophysics, nitrogen abundance measurements help characterize planetary atmospheres and star-forming regions.

Fun fact

Nitrogen in the atmospheres of some exoplanets can form haze particles, similar to the smog on Saturn's moon Titan, which can obscure the planet's surface from telescopes.

Related articles · 24

A Nitrogen Ball Listens to Neutrons
An aluminum sphere the size of a large globe sits in a neutron beam and answers each hit with a precise note. Inside the sphere there is nothing but nitrogen and eleven tiny steel balls, each the size of a pinhead. When a neutron enters the sphere, it knocks a particle out of a nitrogen atom, and that jolt turns into an electrical signal.
Stellar2026-08-263 minarXiv:2608.26097
Chemical Passport for a Star with Seven Planets
Forty light-years away lives a star that went unnoticed for a long time: TRAPPIST-1 emits two thousand times less light than the Sun. But it turned out to have seven Earth-sized planets, three of which orbit in the zone where water could remain liquid. Yet little was known about the star itself, about its chemical kitchen.
The Magnesium Key to Sub-Neptune Interiors
Deep inside a sub-Neptune, where pressures reach a hundred thousand bars and temperatures hit four thousand degrees, rock behaves like boiling soup. Heavy vapors of silicon and magnesium rise, cool, and fall back as a rain of solid particles.
HEP Phenomenology2026-07-282 minarXiv:2607.26128express
How to Catch Ghost Neutrinos in the Mountains
High in the mountains, where the air is clear and still, physicists are preparing to catch elusive visitors from space — neutrinos. These particles, like ghosts, pass straight through the Earth, leaving almost no trace. But occasionally a neutrino does slam into an atom, producing a shower of particles that can be seen.
Galaxies2026-07-272 minarXiv:2607.24929
Cosmic Cross-Pollination: How Galaxies Enrich Their Neighbors with Metals
In 1,433 pairs of galaxies scattered across the sky, astronomers noticed an unusual pattern. Neighbors located 'above' or 'below' a massive stellar system contain up to a quarter more oxygen than those lying in the plane of its disk.
Exoplanets2026-06-292 minarXiv:2606.30644express
How Giant Planets Hide Hydrogen Inside
A sub-Neptune is a planet that falls between Earth and Neptune in size. These worlds are abundant in our galaxy, but their internal structure has been hotly debated. New research shows that in their youth, these planets behave like a sponge soaked with water.
Exoplanets2026-06-241 minarXiv:2606.26075express
A Mirror Planet in the Neptunian Desert
Hundreds of light-years away, there's a planet that looks like a giant mirror. LTT9779b reflects most of the light that hits it — far more than you'd expect from a Neptune-sized body. Astronomers have long debated what makes it so shiny: a thick carbon-rich haze or a layer of clouds. The James Webb Space Telescope has helped settle the debate.
q-bio.BM2026-05-191 minarXiv:2605.19252express
The Chemical Signature of Life: How to Find It by Its Elements
From carbon, nitrogen, oxygen, and sulfur, you can assemble 10⁶⁰ different small molecules: that's a 1 with 60 zeros, more than the stars in the visible universe. Life uses only a tiny fraction of this menu, but not randomly.
Galaxies2026-04-272 minarXiv:2604.24510express
The Scent of the Universe: Benzene Rings in Hot Clouds
In dark, cold clouds of interstellar gas, astronomers have for several years been spotting aromatic molecules — compounds built around a benzene ring (a hexagon of carbon atoms), like the benzene we know. One such substance, benzonitrile (benzene with a cyano group attached), had only been found in very calm and cold places, like the Taurus cloud.
Galaxies2026-04-171 minarXiv:2604.15930express
How Cyanamid Is Born on Ice
In cold clouds between the stars, dust grains are coated with ice, like windows covered with frost in winter. On this icy crust, chemical reactions take place that do not occur in gas. One such reaction is the encounter between a carbon atom and a nitrogen molecule.
Exoplanets2026-04-171 minarXiv:2604.16249express
Ammonia as a Key to Life on Titan
Titan is a cold world with methane lakes and a dense orange atmosphere. But beneath the icy crust, warm puddles may hide, formed after meteorite impacts. In such a puddle, like a chemical flask the size of Selk Crater, simple gases from the air, hydrogen cyanide and acetylene, mix.
Materials2026-04-171 minarXiv:2604.16641express
Nitrogen on the Brink of a Polymer: Two New Phases
Nitrogen, the very gas we breathe, behaves like a finicky metal under a million atmospheres of pressure. In a diamond anvil cell, it is squeezed to 78–98 gigapascals and heated with a laser to 1800–2500 kelvin. Under these conditions, N₂ molecules rearrange into crystals that can store energy more densely than explosives.
High Energy2026-04-171 minarXiv:2604.16650express
Stellar Ash
A neutron star is the remnant of an exploded star, compressed to the size of a city. On its surface, a thermonuclear fire sometimes erupts: accumulated gas explodes like a giant hydrogen bomb. After the burst, ash remains — a mixture of heavy elements that rises to the surface and forms a hot atmosphere.
Exoplanets2026-04-162 minarXiv:2604.15292express
A Carbon Footprint in an Invisible Atmosphere
A world that for years refused to show its face. Planet GJ 1214 b is exactly such a case. It is larger than Earth but smaller than Neptune, and its dense envelope made the atmosphere invisible to telescopes: starlight passed through it without leaving clear traces. But astronomers' persistence and a new sensitive instrument provided the first clue.
Exoplanets2026-03-312 minarXiv:2603.29700express
A Cannabis Signature in the Atmosphere of a Distant Planet
Light from a distant star, passing through the atmosphere of planet K2-18b, left unusual "fingerprints" in its spectrum. Astronomers spent 420 hours collecting this light with the James Webb Space Telescope and split it into colors, like a rainbow.
Exoplanets2026-03-201 minarXiv:2603.20445express
Interstellar Comet: Water 14 Times Heavier Than Earth's
Comet 3I/ATLAS was spotted when it entered the Solar System from interstellar space. The James Webb Telescope split the light from its gas cloud into a rainbow, a spectrum, and in this pattern, the lines of rare molecules with deuterium (heavy hydrogen) appeared.
Exoplanets2026-02-171 minarXiv:2602.16030express
Cosmic Kitchen: How Carbon and Oxygen Shape the Look of Disks
When a chef prepares a dish, not only the proportions of ingredients matter but also their total amount. Two pies with the same sugar-to-flour ratio but made from different batch sizes will turn out differently. So it is with disks around young stars: carbon and oxygen are the key 'spices,' and their absolute amounts change the look of the cosmic 'kitchen' no less than their ratio.
Exoplanets2026-01-131 minarXiv:2601.08390express
Exoplanets2026-01-131 minarXiv:2601.08958express
How Planets Lose Their Volatiles
A young planet grows like a snowball rolling down a slope: countless small pebbles from the surrounding gas disk stick to it. The larger it gets, the stronger it pulls in gas — hydrogen and helium. A dense, hot envelope forms around it. Pebbles falling through it heat up from friction and their own weight, like grains of sand falling into thick honey.
Exoplanets2026-01-091 minarXiv:2601.05480express
Exoplanets2025-10-061 minarXiv:2510.04863express
The Invisible Planet in a Carbon Cocoon: How a Hot Neptune Cheated Death
Astronomers couldn't understand why the 'hot Neptune desert' — a region right next to stars — has almost no Neptune-sized planets. It was thought that there they are doomed: the star's proximity boils off the atmosphere, leaving a bare rocky core. But the exoplanet LTT-9779 b, 29 times heavier than Earth and with a 19-hour orbit, survived.
Stellar2025-10-041 minarXiv:2510.03916express