Will Triton finally answer, ‘Are we alone?’

NASA’s Voyager 2 took this global color mosaic of Neptune’s largest moon, Triton, in 1989. (Credit: NASA/NASA-JPL/USGS)

We recently examined how and why Saturn’s icy moon, Enceladus, could answer the longstanding question: Are we alone? With its interior ocean and geysers of water ice that shoot out tens of kilometers into space that allegedly contains the ingredients for life, this small moon could be a prime target for future astrobiology missions. But Enceladus isn’t the only location in our solar system with active geysers, as another small moon near the edge of the solar system shares similar characteristics, as well. This is Neptune’s largest moon, Triton, which has been visited only once by NASA’s Voyager 2 in 1989. But are Triton’s geysers the only characteristics that make it a good target for astrobiology and finding life beyond Earth?

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Neptune and Its Rings Glow in Webb Telescope’s Portrait

JWST view of Neptune and rings
An infrared image from NASA's James Webb Space Telescope shows Neptune and its rings. Credit: NASA / ESA / CSA / STScI / Joseph DePasquale

The first picture of Neptune to be taken by NASA’s James Webb Space Telescope reveals the latest, greatest details of the ice giant’s atmosphere, moons and rings in infrared wavelengths.

Some of those details — for example, faint bands of dust that encircle Neptune — haven’t been brought to light since the Voyager 2 probe zoomed past in 1989.

“It has been three decades since we last saw those faint, dusty bands, and this is the first time we’ve seen them in the infrared,” astronomer Heidi Hammel, an interdisciplinary scientist on the JWST team who specializes in Neptune, said today in a news release. Neptune’s brighter rings stand out even more clearly.

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Why are Neptune and Uranus Different Colors?

A comparison of Uranus (left) and Neptune (right). Credit: Left: NASA/JPL-Caltech, Right: NASA

Uranus and Neptune are similar planets in many ways. Both are ice giant worlds, both have atmospheres rich in methane, and both have a bluish color. But while Uranus has a pale blue-green hue, Neptune has a deep blue color. But why? Why would two planets so similar in size and composition appear so different? According to a recent study, the answer lies in their aerosols.

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Here are Hubble’s 2021 Photos of the Outer Solar System

The NASA/ESA Hubble Space Telescope has completed its annual grand tour of the outer Solar System for 2021. This is the realm of the giant planets — Jupiter, Saturn, Uranus, and Neptune — extending as far as 30 times the distance between Earth and the Sun. Unlike the rocky terrestrial planets like Earth and Mars that huddle close to the Sun’s warmth, these far-flung worlds are mostly composed of chilly gaseous soups of hydrogen, helium, ammonia, and methane around a packed, intensely hot, compact core. Note: The planets are not shown to scale in this image. Credit: NASA, ESA, A. Simon (Goddard Space Flight Center), and M.H. Wong (University of California, Berkeley) and the OPAL team

If we had to rely solely on spacecraft to learn about the outer planets, we wouldn’t be making great progress. It takes a massive effort to get a spacecraft to the outer Solar System. But thanks to the Hubble Space Telescope, we can keep tabs on the gas giants without leaving Earth’s orbit.

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Why do Uranus and Neptune Have Magnetic Fields? Hot ice

The outer “ice giant” planets, Neptune and Uranus, have plenty of mysteries.  One of the biggest is where exactly they got their magnetic fields.  They are strong at that, with Neptune’s being twenty-seven times more powerful than Earth’s, while Uranus’ varies between ?  and four times Earth’s strength.  Chaos rules in these electromagnetic environments, making them exceptionally hard to both understand and model.  Now a team of researchers led by Dr. Vitali Prakpenka of the University of Chicago thinks they might have found the underlying cause of both the field’s strength and its randomness – “hot ice.”

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Giant Balls of Mush Made From Ammonia and Water Form in the Atmospheres of Uranus and Neptune

One advantage to planetary science is that insights from one planet could explain phenomena on another.  We understand Venus’ greenhouse gas effect from our own experience on the Earth, and Jupiter and Saturn share some characteristics.  But Jupiter also provides insight into other, farther out systems, such as Uranus and Neptune.  Now, a discovery from a spacecraft orbiting Jupiter might have solved a long-standing mystery about Uranus and Neptune – where has all the ammonia gone?

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A 6-Year Search of the Outer Solar System Turns up 461 new Objects (but no Planet 9)

Artist's concept of the New Horizons spacecraft encountering a Kuiper Belt object, part of an extended mission after the spacecraft’s July 2015 Pluto flyby. Credits: NASA/JHUAPL/SwRI

In the near future, astronomers will benefit from the presence of next-generation telescopes like the James Webb Space Telescope (JWST) and the Nancy Grace Roman Space Telescope (RST). At the same time, improved data mining and machine learning techniques will also allow astronomers to get more out of existing instruments. In the process, they hope to finally answer some of the most burning questions about the cosmos.

For instance, the Dark Energy Survey (DES ), an international, collaborative effort to map the cosmos, recently released the results of their six-year survey of the outer Solar System. In addition to gathering data on hundreds of known objects, this survey revealed 461 previously undetected objects. The results of this study could have significant implications for our understanding of the Solar System’s formation and evolution.

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Both Uranus and Neptune Have Really Bizarre Magnetic Fields

These composite images show Uranian auroras, which scientists caught glimpses of through the Hubble in 2011. In the left image, you can clearly see how the aurora stands high above the planet's denser atmosphere. These photos combine Hubble pictures made in UV and visible light by Hubble with photos of Uranus' disk from the Voyager 2 and a third image of the rings from the Gemini Observatory in Hawaii and Chile. The auroras are located close to the planet's north magnetic pole, making these northern lights. Credit: NASA, ESA, and L. Lamy (Observatory of Paris, CNRS, CNES)

The magnetic fields of Uranus and Neptune are really, seriously messed up. And we don’t know why.

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Hubble Releases a New Image of Neptune, Revealing a Rapidly Shifting Storm

This Hubble Space Telescope snapshot of the dynamic blue-green planet Neptune reveals a monstrous dark storm [top center] and the emergence of a smaller dark spot nearby [top right]. CREDITS: NASA, ESA, STScI, M.H. Wong (University of California, Berkeley) and L.A. Sromovsky and P.M. Fry (University of Wisconsin-Madison)

Storms on Neptune seem to follow a pattern of forming, strengthening and then dissipating over the course of about two Earth years. But a Neptunian storm spotted in the planet’s atmosphere over two years ago has done something quite different: it has reversed course and is still going strong.

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Neptune & Triton – August 31, 1989.

Processed using calibrated orange, green, and blue filtered images of Neptune and Triton taken by Voyager 2 on August 31 1989. Image Credit: NASA/JPL-Caltech/Kevin M. Gill

Image-processor extraordinaire Kevin Gill has reached back in time to give us a new image of Neptune and its moon Triton.

When NASA’s Voyager 2 spacecraft flew past Neptune and Triton in August 1989, its cameras were very busy. Kevin has taken separate color-filtered images from that visit and calibrated and combined them to give us a new, almost haunting look at the planet and its largest moon.

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