The accelerating expansion of the universe
Astronomers, using the Keck telescopes to study the speeds at which a certain type of exploding star were flying apart, were shocked to discover that the universe is speeding up in its expansion. They had found evidence of a mysterious repulsive force in physics: dark energy. The 2011 Nobel Prize in Physics was awarded for this ground-breaking research to Saul Perlmutter of UC Berkeley and Lawrence Berkeley National Laboratory; Brian P. Schmidt of Australian National University; and Adam G. Riess of Johns Hopkins University.
Oodles of exoplanets
Sixteen years ago, astronomers at Keck detected the first planet outside of our solar system by applying the Doppler effect to spectroscopy. Today, more than 1,000 such discoveries later, Keck has found the majority of all known exoplanets.
Black hole in the Milky Way
Using the Keck II telescope's infrared adaptive optics, astronomers looked through the dust and gas that block our visible light view into the center of our own Milky Way galaxy. What they found were hundreds of large young stars in rapid orbits around some unseen, incredibly massive object. It was profoundly convincing evidence of the existence of a supermassive black hole 4 million times the mass of our sun at the center of the galaxy. Since then, it is generally agreed that most galaxies have black holes at their center.
Catching Pluto's killer
After discovering what appeared to be an object larger than Pluto in the outer solar system in 2005, Caltech's Mike Brown and his team quickly turned to the Keck II telescope and its atmosphere-penetrating adaptive optics to get a brighter, clearer look. They were surprised to discover a moon orbiting the object. That helped them establish that the object, later named Eris, was larger than Pluto, but otherwise extremely similar to the former ninth planet. Brown's research led to the demise of Pluto as a planet, and introduced to the public an entirely new population of cosmic objects in our solar system now known as "dwarf planets."
Planet construction zones around a nearby star
In 1998, astronomers on the Keck II telescope discovered evidence of a budding solar system around a moderately young star 220 light years away from Earth. The powerful capabilities of the Keck allowed observers to determine that a dust ring around the star was a critical missing link in the evolution of solar systems.
L & T dwarfs: a new class of stars
After a number of brown dwarf candidates were identified, the Keck Observatory was used to obtain spectra to reveal the chemical makeup and temperature of more than 200 objects. In those findings, two classes of yet unclassified stars revealed themselves: the hotter "L dwarf" and the cooler "T dwarf." Because of the unique range in temperature and chemical makeup the objects displayed, a century-old definition had to be rewritten.
Shoemaker-Levy comet collides with Jupiter
While not a discovery, the collision of comet Shoemaker-Levy 9 into the largest planet in our solar system was arguably astronomy's most exciting week during Keck's first decade in operation. After a near miss in July 1992, Jupiter's huge tidal force ripped the comet apart sending 20 fragments in a wild, fatal orbit that lasted until July 1994 when they crashed into the giant planet. Over six days, the Keck telescopes were positioned to take some of the best images of the exciting impact.
Measure distances of faraway galaxies
For the first time, spectroscopy gathered from Keck telescopes has allowed astronomers to obtain not only accurate distance to large numbers of very distant galaxies, but their stellar velocities, mass and their chemical composition as well. This work is continuing using similar methods to make the connection between early galaxies and the diffuse "intergalactic medium" between the galaxies.
Using gravitational lensing to find early galaxy
What do you get when you team the world's most powerful telescope with gravitational lensing? A peek at one of the youngest building blocks of the universe. Gravitational lensing, as Einstein theorized, bends lights rays from an object behind a larger object, allowing it to appear much brighter than if it were "alone." A group led by Caltech's Richard Ellis used the technique and the superior light-gathering power of the Keck telescopes to see a system of about a million stars that was forming in the first half-billion years of the universe.