Stars are heavenly bodies that originated in darkness. All of the twinkling points of light in the night sky were once born in inky black clouds that wander through the vast expanses of the Milky Way.

The maximum temperature in these ghostly clouds is minus 250 degrees Celsius (minus 418 degrees Fahrenheit); indeed the clouds are hardly any warmer than space itself. Furthermore, their density initially is almost as low as that of a vacuum, with a volume the size of the Pacific Ocean containing but a single gram of hydrogen.These widely dispersed gas atoms are the raw material from which stars are born. But it takes eons for the thin, icy strips of clouds to condense into compact, hot balls of fire. First, clumps must form within the clouds of gases and dust, with particles attracting one another and flying together at supersonic speeds. In the end, extreme pressure builds in the center of the increasingly dense ball of gas, and thermonuclear fusion in the hydrogen core begins. It is the fire of the new star.

This, at any rate, is the theory, based on computer simulations. No one has actually seen the birth and growth of suns. To the regret of astronomers, all of these processes are either invisible in the early stages or are hidden in the late stages. The gas-and-dust clouds surround the growing stars like a protective cocoon, preventing all light from escaping. The precise details of how a star is born remain a mystery.

Now astrophysicists are taking a new approach to gazing at the places where stars are born. Even the icy, dark clouds emit thermal radiation. While such waves are invisible to the human eye, the world’s most unusual telescope, which stares into space from an aircraft, is now being used to intercept the infrared signals.

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