It is very likely that at the next birthday party you attend you will find yourself surrounded by the chemical element helium. Count yourself lucky as helium, the gas that keeps those birthday balloons floating in midair, is quite rare here on Earth.

Helium (He) may be the second most abundant element in the universe (hydrogen takes top spot) but it only makes up 0.0005 percent of the volume of our planet’s atmosphere. That’s because as the second lightest chemical element (again beaten out by hydrogen), it floats up into space, escaping Earth’s gravity.

Helium makes up about 24 per cent of the mass of the universe, and about 27 per cent of the sun’s mass. And most of the helium in our universe was created in the first three minutes following the big bang!

Helium was detected in space before it was discovered here on Earth. In 1868! In that year an astronomer in India noticed a bright yellow spectral line emanating from the sun when he observed a solar eclipse through a prism. A second astronomer in England observed a similar yellow line later that year. The unknown element was named after the Greek God of the sun, Helios. Scientists believed that helium only existed on the sun until 1882 when an Italian physicist observed a similar yellow spectral line in lava from an erupting Mount Vesuvius.

Even though our gravity can’t keep helium here on Earth it is continually being replenished. Radioactive decay of other elements in the Earth’s crust as well as rays from the sun keep our planet supplied.

Sound travels through helium three times faster than it does through air.  When someone breathes in the gas, sound waves bounce around the vocal tract faster than they do when air is inhaled. This makes the higher frequencies of the voice louder, making us sound high-pitched and a little duck-like when we speak. While the gas is non-toxic, breathing helium is not considered safe as it takes the place of the oxygen we need for respiration.

Helium is not just for birthdays! You can find it used in medical treatments for breathing problems such as asthma, in the oxygen tanks of deep-sea divers, in the manufacture of fibre optic cables for the internet, to clean rocket fuel tanks, to cool magnetic coils in MRI machines, to detect leaks in the hulls of ships, to deploy airbags in cars and it is used to produce phone, computer and tablet chips.

When helium is cooled to near absolute zero, it becomes a superfluid. In that unique state it has the density of 1.8^th of water and zero friction and can flow through openings the size of a molecule. It can also move along a surface, travelling upwards against the force of gravity.

About 400,000 cubic feet of helium keeps the Macy’s Thanksgiving Day Parade balloons aloft. You would need the equivalent of about 30,000 party balloons worth of helium to keep just one of the characters floating along the parade route!

Article originally published in Brainspace Magazine Winter 2022.