The Sky of the Day Humanity Opened an Eye on Infinity
On April 24, 1990, at 12:33 UTC, the Space Shuttle Discovery tore away from Launch Pad 39B at the Kennedy Space Center, carrying in its cargo bay the Hubble Space Telescope. This 13-meter cylinder, weighing 11 tons, would become the most transformative scientific instrument in the history of astronomy. This star map captures the celestial vault above Cape Canaveral at the moment of launch — the last instant when humanity gazed at the stars without the aid of the eye that would see to the edge of the observable universe.
Historical context
On April 24, 1990, the Space Shuttle Discovery stood upright on Launch Pad 39B at the Kennedy Space Center, surrounded by wisps of liquid oxygen venting from its orange external tank. Inside its 18-meter cargo bay, a silver cylinder the size of a school bus waited patiently: the Hubble Space Telescope, the most ambitious and most troubled project in the history of NASA.
The telescope was named after Edwin Hubble, the American astronomer who in 1929 had discovered that the universe was expanding — a revelation so profound that Einstein himself had been forced to modify his equations to accommodate it. Hubble had observed that distant galaxies were moving away from us, and that the farther they were, the faster they fled. The universe was not static. It had had a beginning. There had been a Big Bang.
But observing the edges of this expanding universe from Earth's surface posed a fundamental problem: the atmosphere. This thin layer of gas that allows us to breathe also distorts starlight. It is what makes stars twinkle — a romantic spectacle for poets, but a nightmare for astronomers. As early as the 1940s, astrophysicist Lyman Spitzer had proposed placing a telescope in orbit, above the turbulent atmosphere. It would take forty years of lobbying, design, and construction to turn that vision into reality.
At 12:33 UTC, Discovery's five engines roared and the shuttle climbed into the Florida sky, leaving behind a column of smoke and flame visible for miles around. On board, five astronauts — Loren Shriver, Charles Bolden, Bruce McCandless, Kathryn Sullivan, and Steven Hawley — had the mission of placing Hubble into orbit at an altitude of 600 kilometers.
The following day, April 25, Discovery's robotic arm gently lifted the telescope out of the cargo bay and released it into the void of space. Its solar panels unfurled, its antennas pointed toward relay satellites, and the most powerful eye ever built by humanity opened upon the universe. Or at least, that is what should have happened.
Because Hubble had a flaw. Its 2.4-meter primary mirror — polished to a precision of one sixty-four-thousandth of a millimeter — had a spherical aberration. The edge of the mirror had been ground 2.2 micrometers too flat, an error of a minute fraction of the thickness of a human hair. But it was enough to render the images blurry. Hubble's first photographs, instead of the crystalline visions promised, showed stars surrounded by a hazy halo. The 1.5-billion-dollar telescope was nearsighted.
The news made headlines around the world. Hubble became the butt of comedians' jokes. NASA was humiliated. For three years, engineers worked frantically to design "corrective glasses" for the telescope — an optical device called COSTAR that would compensate exactly for the mirror's defect. In December 1993, during a spectacular servicing mission, astronauts installed COSTAR and replaced the defective instruments. When the first corrected images reached Earth, scientists wept. The universe, at last, appeared in supernatural clarity.
What sky stretched above Cape Canaveral at the moment of launch? On that April 24, the Florida sun blazed high in a deep blue sky. The Sun sat in the constellation Aries, high in the sky at launch time. Although the stars were invisible in broad daylight, the celestial configuration of that spring 1990 was remarkable.
In the night sky that had preceded the launch, Leo the lion dominated the firmament, with Regulus shining like a beacon above the Atlantic. Virgo was rising in the east, carrying in her arms the star Spica, a pure blue-white brilliance. Boötes, with flamboyant Arcturus, pointed toward the zenith. The Big Dipper, the most recognizable figure in the northern sky, faithfully indicated Polaris, that immutable axis around which the entire sky appears to turn. Jupiter gleamed in Cancer, adding its golden radiance to the tableau.
Over the following thirty years, Hubble would transform our understanding of the universe immeasurably. It was Hubble that photographed the Pillars of Creation — those columns of gas and dust in the Eagle Nebula where new stars are born. It was Hubble that made it possible to measure the age of the universe with precision: 13.8 billion years. It was Hubble that revealed that the expansion of the universe was accelerating, leading to the discovery of dark energy. It was Hubble that plunged its gaze into the apparent emptiness of a tiny square of sky — the Hubble Deep Field — and discovered thousands of galaxies there, each containing hundreds of billions of stars.
The Hubble Space Telescope remains in orbit today, more than thirty years after its launch, continuing to send back images that push the boundaries of our understanding. On that April 24, 1990, beneath the blue sky of Florida, humanity sent an eye of glass and metal beyond the atmosphere — and that eye showed it a universe vaster, older, and more beautiful than anything it had ever imagined.