Helium

Escaped from Earth, Discovered in the Sun

Atomic Number: 2 | Symbol: He | Category: Noble Gas

Helium was detected in the Sun's spectrum during an 1868 eclipse before it was found on Earth, making it the only element first discovered beyond our planet. French astronomer Pierre Janssen and British scientist Norman Lockyer independently observed mysterious yellow spectral lines that matched no known element. Named after Helios, the Greek sun god, helium remained a solar mystery until 1895 when Scottish chemist William Ramsay isolated it from uranium ore. This second-lightest element refuses to bond with other atoms under normal conditions, and its atoms move so fast that Earth's gravity cannot retain them—helium constantly escapes into space. Today helium chills superconducting magnets in MRI machines, lifts scientific balloons to the stratosphere, and provides the inert atmosphere needed for advanced manufacturing.

The Inert Mystery

Helium reacts with virtually nothing because its two electrons completely fill its first electron shell, creating perfect stability. For over a century, chemists believed helium compounds were impossible—unlike its fellow noble gases xenon and krypton, which form exotic molecules under extreme conditions. In 2017, researchers finally synthesized sodium helide (Na₂He) at pressures exceeding 1 million atmospheres, proving even helium's aloofness has limits. This non-reactivity makes helium ideal for purging rocket fuel lines, protecting delicate welds from oxidation, and preventing combustion in environments where other gases would explode. Deep-sea divers breathe helium-oxygen mixtures to avoid nitrogen narcosis below 100 feet. Helium's chemical indifference frustrates efforts to trap it—no material can chemically bind it.

Voices and Buoyancy

Helium-filled balloons float because helium's density is one-seventh that of air, providing lift of about one gram per liter at sea level. The Goodyear blimp holds 200,000 cubic feet of helium, generating 12,000 pounds of lift. Inhaling helium raises voice pitch because sound travels three times faster through helium than air, shifting vocal tract resonances higher. This party trick carries risks—helium displaces oxygen, and prolonged inhalation causes asphyxiation. Weather balloons carry helium to altitudes exceeding 120,000 feet where atmospheric pressure drops to 1% of sea level, causing the balloons to expand thirty-fold before bursting. Google's Project Loon used helium balloons to provide internet access to remote areas before shutting down in 2021.

Supercool Technology

Liquid helium reaches 4.2 Kelvin at atmospheric pressure, cold enough to make metals superconducting with zero electrical resistance. MRI machines require approximately 2,000 liters of liquid helium to maintain superconducting magnets that generate the powerful fields needed for medical imaging. The Large Hadron Collider uses 96 tons of liquid helium to cool 1,600 superconducting magnets to 1.9 Kelvin—colder than outer space. Below 2.17 Kelvin, helium-4 becomes a superfluid with zero viscosity, flowing up and over container walls and conducting heat hundreds of times better than copper. This phase can flow through impossibly small channels and creates bizarre fountain effects when heated. Helium-3, a rare isotope, enables even lower temperatures approaching absolute zero in dilution refrigerators used for quantum computing research.

Primordial Abundance

Helium formed in the Big Bang's first three minutes when the universe was hot enough for nuclear fusion, creating about 25% of all ordinary matter by mass. This primordial helium provides crucial evidence for the Big Bang theory—the ratio of helium to hydrogen matches predictions from Big Bang nucleosynthesis models. Stars produce additional helium by fusing hydrogen, gradually enriching galaxies over billions of years. Gas giants like Jupiter contain massive helium reserves—Jupiter's atmosphere is roughly 24% helium by mass. The Sun converts 600 million tons of hydrogen into helium every second. Helium constitutes approximately 23% of the observable universe's elemental mass, second only to hydrogen.

The Helium Shortage

Earth's helium comes entirely from radioactive decay of uranium and thorium deep underground, where alpha particles—helium nuclei—accumulate in natural gas deposits over millions of years. Unlike other elements, helium cannot be manufactured or synthesized artificially. The United States controlled 80% of global reserves throughout the 20th century, primarily from fields in Texas, Kansas, and Oklahoma. Since 1996, the U.S. government has been selling off the Federal Helium Reserve, causing price volatility and periodic shortages. Qatar and Algeria now compete as major suppliers. Current consumption rates suggest accessible reserves may last only 25-30 years, threatening research and medical technologies. Helium released into the atmosphere escapes to space permanently within a few million years.

Alpha Particles Unmasked

Ernest Rutherford proved in 1907 that alpha particles emitted during radioactive decay were actually helium nuclei—two protons and two neutrons stripped of electrons. This discovery explained mysterious helium accumulations in uranium-rich minerals and revealed fundamental nuclear processes. Radon gas, found in basements worldwide, decays into radioactive polonium while ejecting helium nuclei. Marie Curie's radium samples continuously generated helium through alpha decay. Modern smoke detectors use americium-241, which emits alpha particles to ionize air and detect smoke. Alpha radiation cannot penetrate human skin but causes severe damage if radioactive materials are inhaled or ingested, as the high-energy helium nuclei tear through cellular tissue.

Part of the Periodic Tales collection