Keck Observatory Archives

August 24, 2023August 24, 2023 by Nancy Atkinson

Neptune's Cloud Cover is Linked to the Solar Cycle

This sequence of Hubble Space Telescope images chronicles the waxing and waning of the amount of cloud cover on Neptune. Credits: NASA, ESA, Erandi Chavez (UC Berkeley), Imke de Pater (UC Berkeley)

Whenever Neptune reaches its closest point in the sky to Earth, its portrait is taken by the Hubble Space Telescope and other ground-based observatories. Watching the planet from 1994 to 2020, astronomers have made puzzling discovery.

The clouds in Neptune’s atmosphere appear to be to be linked to the solar cycle and not the planet’s cycle of seasons. The global cloud cover seems to come and go in a cycle that apparently syncs up with the Sun’s 11-year cycle, as it shifts from solar maximum to solar minimum or vice versa. This is surprising since Neptune is so far from the Sun and receives about 0.1% of Earth’s sunlight.

June 29, 2023June 29, 2023 by Laurence Tognetti

A Direct Image of a Planet That’s Just Like Jupiter, Only Younger

Direct images of the extrasolar planet, AF Lep b (white spot around 10 o’clock), orbiting its host star (center) taken in Dec. 2021 and Feb. 2023 using the W. M. Keck Observatory’s 10-meter telescope in Hawai?i. (Credit: Kyle Franson, University of Texas at Austin/W. M. Keck Observatory)

In a recent study published in The Astrophysical Journal Letters, a team of astronomers used the W. M. Keck Observatory on Maunakea, Hawai?i Island to identify exoplanet, AF Lep b, which is three times the mass of Jupiter orbiting a Sun-sized star located approximately 87.5 light-years from Earth. What makes this discovery unique is AF Lep b is the first exoplanet discovered using a method called astrometry, which involves measuring unexpected, miniscule changes in the position of a star relative to nearby stars, which could indicate another object, an exoplanet, is causing gravitational tugs on its parent star.

June 19, 2023June 19, 2023 by Andy Tomaswick

Can We Predict if a System Will Have Giant Planets?

Prediction is one of the hallmarks of scientific endeavors. Scientists pride themselves on being able to predict physical realities based on inputs. So it should come as no surprise that a team of scientists at Notre Dame has developed a theory that can be used to predict the existence of giant planets on the fringes of an exoplanetary system.

February 20, 2023February 20, 2023 by Matt Williams

All of Jupiter's Large Moons Have Auroras

Artist's concept of aurorae on Ganymede - auroral belt shifting may indicate a subsurface saline ocean. Credit: NASA/ESA

Jupiter is well known for its spectacular aurorae, thanks in no small part to the Juno orbiter and recent images taken by the James Webb Space Telescope (JWST). Like Earth, these dazzling displays result from charged solar particles interacting with Jupiter’s magnetic field and atmosphere. Over the years, astronomers have also detected faint aurorae in the atmospheres of Jupiter’s largest moons (aka. the “Galilean Moons“). These are also the result of interaction, in this case, between Jupiter’s magnetic field and particles emanating from the moons’ atmospheres.

Detecting these faint aurorae has always been a challenge because of sunlight reflected from the moons’ surfaces completely washes out their light signatures. In a series of recent papers, a team led by the University of Boston and Caltech (with support from NASA) observed the Galilean Moons as they passed into Jupiter’s shadow. These observations revealed that Io, Europa, Ganymede, and Callisto all experience oxygen-aurorae in their atmospheres. Moreover, these aurorae are deep red and almost 15 times brighter than the familiar green patterns we see on Earth.

December 2, 2022December 2, 2022 by Nancy Atkinson

New Images of Titan From JWST and Keck Telescopes Reveal a Rare Observation

Evolution of clouds on Titan over 30 hours between November 4 and November 6, 2022, as seen by Webb NIRCam (left) and Keck NIRC-2 (right). Credit: SCIENCE: NASA, ESA, CSA, Webb Titan GTO Team IMAGE PROCESSING: Alyssa Pagan (STScI).

Planetary scientists have greatly anticipated using the James Webb Space Telescope’s infrared vision to study Saturn’s enigmatic moon Titan and its atmosphere. The wait is finally over and the results are spectacular. Plus, JWST had a little help from one of its ground-based observatory friends in helping to decode some strange features in the new images. Turns out, JWST had just imaged a rare event on Titan: clouds.

November 10, 2022November 10, 2022 by Scott Alan Johnston

Keck's new Planet Hunter Instrument Comes Online, Searching for Smaller, More Earth-Sized Exoplanets

There’s a new planet hunter in town, and it’s got its sights set on nearby Earth-sized planets in the galactic neighborhood.

February 21, 2022February 21, 2022 by Andy Tomaswick

Twin Brown Dwarfs Discovered, Orbiting one Another at Three Times the Distance From the Sun to Pluto

Gravity is a funny force. The gravity of every given object technically impacts every other given object, though, in practice, large distance and small masses make those forces negligible for such interactions. But in some cases, especially when large groups are floating in empty space, gravity can still hold sway over considerable distances. Such is the case with a new pair of brown dwarfs found by astronomers at the Keck Observatory.

January 18, 2022January 18, 2022 by Evan Gough

These Newly-Discovered Planets are Doomed

An artist’s rendition of what a planetary system similar to TOI-2337b, TOI-4329b, and TOI-2669b might look like, where a hot Jupiter-like exoplanet orbits an evolved, dying star. Image Credit: Karen Teramura/University of Hawai?i Institute for Astronomy

Astronomers have spied three more exoplanets. But the discovery might not last long. Each planet is in a separate solar system, and each orbits perilously close to its star. Even worse, all of the stars are dying.

The results?

Three doomed planets.

January 12, 2022January 12, 2022 by Evan Gough

Astronomers Watch a Star Die and Then Explode as a Supernova

Artist's impression of a supernova. Credit: NASA

It’s another first for astronomy.

For the first time, a team of astronomers have imaged in real-time as a red supergiant star reached the end of its life. They watched as the star convulsed in its death throes before finally exploding as a supernova.

And their observations contradict previous thinking into how red supergiants behave before they blow up.

July 14, 2021January 11, 2022 by Andy Tomaswick

From the way These Stars Look, a Supernova is Inevitable

Sometimes loud explosions are easier to deal with when you know they’re coming. They are also easier to watch out for. So when astronomers from the University of Warwick found a rare tear-drop shaped star, known as HD265435, they knew they were looking at a potential new supernova waiting to happen. The only caveat – it might not actually happen until 70 million years from now.