Harry Clement Stubbs, that’s his real name, was born on May 30, 1922, in Somerville, Massachusetts.

Hal Clement studied at Harvard, where he graduated with a B.S. in astronomy in 1943. While still attending college, he published his first story, “Proof”, in the June 1942 issue of the magazine “Astounding Science Fiction”.

During World War II, Hal Clement served as a pilot and copilot of a B-24 Liberator flying in several missions over the skies of Europe. After the war, he served in the U.S. Air Force Reserve and retired with the rank of colonel.

For many years, Hal Clement taught astronomy and chemistry at Milton Academy in Milton, Massachusetts.

In 1950, Hal Clement published his first novel, “Needle”, in which one of the protagonists is an alien capable of living in symbiosis with other creatures, in the novel with a human being.

In 1953, Hal Clement published his novel “Iceworld”, which has the interesting feature of having a point of view opposite to the usual one as it’s the story of an alien forced to go on a planet that is very cold to him, the Earth.

In 1954, Hal Clement published his most famous novel, “Mission of Gravity”, set on Mesklin, a gas giant planet that has the shape of a flattened ellipsoid and spins in just over two hours, causing strong variations in gravity between the poles and the equator. In 1961, Clement published a sequel titled “Star Light”. Over the years, he wrote other stories set on the planet Mesklin, collected in the anthology “Heavy Planet”.

In 1964, Hal Clement published “Close to Critical”, set on another quite exotic planet inhabited by intelligent aliens.

In 1978, Hal Clement published “Through the Eye of a Needle”, the sequel to “Needle”.

In 1996, Hal Clement received a Retro Hugo Award for his short story “Uncommon Sense”. In 1998 he received the Grand Master Award from the Science Fiction and Fantasy Writers of America (SFWA).

In 2003, Hal Clement published his last novel, “Noise”. He died on October 29, 2003, in Milton, Massachusetts, probably because of the complications of diabetes he suffered from.

Hal Clement wrote stories in which the scientific element was important but at the same time full of sense of wonder, creating alien environments such as the one of the planet Mesklin, definitely exotic yet very plausible. He started writing fiction at a time when contacts between humans and aliens were generally belligerent but in his stories, they were usually friendly. He wasn’t a prolific writer but these qualities of his stories made him important in the history of science fiction.