Studying the Planets and Moons - NASA Science

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Hubble’s long presence in space and regular observations of the planets — Jupiter, Saturn, Uranus, Neptune, and Mars — give planetary astronomers the opportunity to study their ever-changing atmospheres and curious moons, charting the changes of these dynamic systems.

The Planets

Capturing the Aftermath of Impacts on Jupiter

In 1994, just four years into its long tenure of collecting data, Hubble watched as 21 fragments of Comet Shoemaker-Levy 9 (SL9) bombarded the giant planet Jupiter with a sequential train of impacts. Each fragment left a temporary black scar that revealed deeper layers of the planet’s atmosphere. It was the first time astronomers witnessed such an event. Hubble observed another impact in 2009, when a suspected asteroid plunged into Jupiter’s atmosphere and left a temporary dark feature the size of the Pacific Ocean.

How Historic Jupiter Comet Impact Led to Planetary Defense

Shoemaker-Levy 9 Impacts on Jupiter
R. Evans, J. Trauger, H. Hammel and the HST Comet Science Team, and NASA

Comet Shoemaker-Levy 9 left an indelible mark on our understanding of the solar system when it collided with Jupiter. Discover the significance of this event and the crucial role Hubble played in capturing its dramatic impact. Join us on a journey to explore the dynamic forces that shape our solar system, unveiling the intricate interactions between comets and planets. In this video, Dr. Heidi Hammel delves into the story of Comet Shoemaker-Levy 9 and highlights the importance of Hubble's contributions.

NASA's Goddard Space Flight Center; Producer: James Leigh

Monitoring Jupiter’s Shrinking Red Spot

Using Hubble, astronomers tracked Jupiter’s Great Red Spot, a giant swirling storm slightly larger than Earth, and found that it is shrinking and jiggling. The spot’s outer winds are speeding up while moving significantly more slowly toward its center.

Hubble Shows Winds in Jupiter’s Great Red Spot Are Speeding Up

Jupiter’s Shrinking, Jiggling Red Spot
NASA, ESA, Amy Simon (NASA-GSFC); Image Processing: Joseph DePasquale (STScI)

Like the speed of an advancing race car driver, the winds in the outermost “lane” of Jupiter’s Great Red Spot are accelerating – a discovery only made possible by NASA’s Hubble Space Telescope, which has monitored the planet for more than a decade. Researchers analyzing Hubble’s regular “storm reports” found that the average wind speed just within the boundaries of the storm, known as a high-speed ring, has increased by up to 8 percent from 2009 to 2020. In contrast, the winds near the red spot’s innermost region are moving significantly more slowly, like someone cruising lazily on a sunny Sunday afternoon.

NASA's Goddard Space Flight Center; Lead Producer: Paul Morris

Studying Auroras

Hubble captured brilliant curtains of light, called auroras, on Jupiter, Saturn, and Uranus. Auroras develop when electrically charged particles trapped in a planet’s magnetic field spiral inward at high speeds toward the north and south magnetic poles. When these particles hit the upper atmosphere, they excite atoms and molecules there, causing them to glow in a similar process to that of a neon light.

NASA’s Spacecraft Help Solve Saturn’s Mysterious Auroras

Saturn Aurora
NASA, ESA, J. Clarke (Boston University), and Z. Levay (STScI)

This composite video illustrates the auroras on Jupiter relative to their position on the giant planet. The Jupiter auroras observed by Hubble are some of the most active and brightest ever caught by the telescope, reaching intensities over a thousand times brighter than those seen on Earth. Hubble's sensitivity to ultraviolet light captures the glow of the auroras above Jupiter's cloud top. The auroras were photographed on May 19, 2016, during a series of far-ultraviolet-light observations taking place as NASA's Juno spacecraft approaches and enters into orbit around Jupiter.

NASA, ESA, J. Nichols (University of Leicester), and G. Bacon (STScI); Acknowledgment: A. Simon (NASA/GSFC) and the OPAL team

Discovering a Link Between Neptune’s Clouds and the Sun

Hubble expanded upon the NASA Voyagers’ observations of Neptune and Uranus. It found that Neptune’s southern hemisphere ‘Great Dark Spot’ vanished in 1994, then spotted another dark storm in Neptune’s northern hemisphere a year later. Hubble’s decades of observations revealed that Neptune’s storms last for a few years before vanishing or fading away and that this cycle correlates to the Sun’s cycle of activity.

Neptune’s Disappearing Clouds Linked to the Solar Cycle

Neptune’s Clouds and the Sun’s Cycle
NASA, ESA, LASP, Erandi Chavez (UC Berkeley), Imke de Pater (UC Berkeley)

Hubble observations show that Neptune's clouds are almost completely disappearing! Astronomers report that their continual monitoring of Neptune’s weather uncovered a link between its shifting cloud abundance and the 11-year solar cycle, where the Sun’s activity waxes and wanes under the driving force of its entangled magnetic field.

NASA's Goddard Space Flight Center; Producer: Paul Morris

Saturn’s Rings Heating Its Atmosphere

Hubble also helped astronomers calibrate archival Saturn data from four separate missions. The precision of Hubble’s Space Telescope Imaging Spectrograph (STIS) and its ability to see ultraviolet light, allowed researchers to compare STIS UV observations of Saturn to 40 years of UV data from the Voyager and Cassini missions, and the International Ultraviolet Explorer. They discovered that icy ring particles raining on Saturn’s atmosphere at specific latitudes and seasonal effects cause atmospheric heating. Researchers are testing to see if this unexpected interaction can help define new ways of examining distant exoplanets for extended Saturn-like ring systems.

Hubble Finds Saturn’s Rings Heating Its Atmosphere

Saturn
NASA, ESA, Lotfi Ben-Jaffel (IAP & LPL)

Hubble images of Saturn herald the start of the planet’s “spoke season” surrounding its equinox, when enigmatic features appear across its rings. The cause of the spokes, as well as their seasonal variability, has yet to be fully explained by planetary scientists, but they may be the result of icy ring particle.

NASA's Goddard Space Flight Center; Producer: Paul Morris

Studying the Dynamic Martian Atmosphere

Hubble offers planetary astronomers the opportunity to studying global Martian weather. Hubble has charted the evolution of Martian sandstorms, the waxing and waning the planet’s polar ice caps, and seasonal changes in the planet’s cloud cover and atmospheric composition.

Hubble Sees A Perfect Dust Storm on Mars

Left: Partly Cloudy Day on Mars, Right: Mars Enshrouded in a Sandstorm
NASA/ESA, James Bell (Cornell Univ.), Michael Wolff (Space Science Inst.), and the Hubble Heritage Team (STScI/AURA)

Their Moons

Finding Water on Jupiter’s Moons

Hubble found the best evidence yet for an ocean of liquid under an ice crust on Jupiter’s moon Ganymede, the largest moon in the solar system. This ocean may have more water than all of Earth’s surface. Hubble also recorded evidence of short-lived changes in the atmosphere above the surface of Jupiter’s moon Europa – the likely result of gas plumes expelled from a subsurface ocean.

NASA’s Hubble Spots Possible Water Plumes Erupting on Jupiter’s Moon Europa

Plumes on Jupiter’s Moon Europa
NASA, ESA, and W. Sparks (STScI); Illustration: NASA, ESA, W. Sparks (STScI), and the USGS Astrogeology Science Center
Finding New Moons

In 2003, astronomers using Hubble discovered two small moons around Uranus, called Cupid and Mab. The moons are about 8 to 10 miles across (12-16 km), or roughly the size of San Francisco. Hubble also detected two large outer rings around Uranus.
Ten years later researchers found a small, faint moon called Hippocamp in images Hubble took of Neptune between 2004 and 2009. Astronomers discovered the moon while studying faint ring-arcs around the planet. Then they combed through 150 archived Hubble images of Neptune looking for the moon. Using those Hubble images, they were able to plot Hippocamp’s 23-hour orbit around Neptune.

Hubble Finds Additional Moons and Rings Around Uranus

New Moons Around Neptune
NASA, ESA, and M. Showalter (SETI Institute)

From its vantage point high above Earth’s atmosphere, Hubble makes an annual grand tour of the outer solar system – returning crisp images that are almost as good as earlier snapshots from interplanetary spacecraft. 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.

NASA's Goddard Space Flight Center; Lead Producer: Paul Morris

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four Hubble images of Jupiter during Shoemaker-Levy impact

Comet Fragment Slams Into Jupiter

In July 1994, 21 chunks of comet Shoemaker-Levy 9, which had broken apart a year earlier, slammed into Jupiter, and Hubble recorded this spectacular event.

The orange and yellow clouds of a close-up view of Jupiter fill the image. A dark marron elongated oval reveals the site of an asteroid impact.

Hubble Images Suggest Rogue Asteroid Smacked Jupiter

Without warning, a mystery object struck Jupiter on July 19, 2009, leaving a dark bruise the size of the Pacific Ocean.

Blue aurora on top of jupiter

Hubble Captures Vivid Auroras in Jupiter’s Atmosphere

Hubble photographed Jupiter’s auroras during a series far-ultraviolet-light observations taking place as NASA’s Juno spacecraft approached and entered its orbit around Jupiter.

Yellow, rust, and white bands visible on Saturn. The planet is tilted, such that its rings extend from upper-left to lower-right. A blue-white, glowing ring (the auroras) is visible at the bottom of the planet's sphere. All on a black background.

Saturn’s Auroras Defy Scientists’ Expectations

Hubble observations of Saturn helped researchers overturn theories about how Saturn’s magnetic field behaves and how its auroras are generated.

A series of eight images of Neptune: four on the upper half of the image and four on the lower half of the image. The planet appears as a dark-blue sphere dotted with bright white patches.

Neptune’s Disappearing Clouds Linked to the Solar Cycle

As sunspots come and go, so does the cloudy weather on the blue giant planet.

An image of Saturn. Its rings stretch across the image from the upper-left to the lower-right. The rings appear dark blue, nearly black. The planet is a series of dark blue, blue, light blue, and white bands.

Hubble Finds Saturn’s Rings Heating Its Atmosphere

Saturn’s vast ring system is heating the giant planet’s upper atmosphere.

Two images Hubble images of Mars. The left image was taken on 26 June 2001 and shows Mars with its polar caps and a few white clouds. The right image was taken on 4 September 2001 and shows the planet enshrouded in a dust storm.

Scientists Track “Perfect Storm” on Mars

The Martian dust storm, larger by far than any seen on Earth, has raised a cloud of dust that engulfed the entire planet for several months.

On a black background, a large orange and white orb is surrounded by a diffuse, grainy, orange halo. The halo appears to have more material on its right side than its left.

NASA’s Hubble, MAVEN Help Solve Mystery of Mars’ Escaping Water

Scientists know that over the last 3 billion years, at least some Martian water went deep underground, but what happened to the rest?

Two Side-by-side images of Europa showing a white plume extending from the moon's limb. Left image was takin in 2014, right in 2016.

Hubble Spots Possible Venting Activity on Europa

Recent Hubble uncovered a probable plume erupting from the moon’s surface at precisely the same location as one seen two years earlier.

Artist concept of Ganymede and Jupiter. Spiky blue auroras flare from Ganymede's surface.

Hubble Observations Suggest Underground Ocean on Ganymede

Though the presence of an ocean on Ganymede has been long predicted based on theoretical models, Hubble found the best evidence for it.

Hubble Spies Tiny Moons Circling Uranus

Two new moons, uncovered by Hubble, are so faint they eluded the Voyager 2 spacecraft when it flew by Uranus in 1986.

Newly Discovered Moons and Rings of Uranus (Annotated). Two images of Uranus on its side, with its rings and planets orbits shown vertically. Uranus is an aqua sphere with white areas near the poles.

Hubble Discovers New Rings and Moons Around Uranus

Hubble’s high sensitivity and sharp view has uncovered a pair of giant rings girdling the planet. The largest is twice the diameter of the planet’s previously known ring system, first discovered in the late 1970s. Hubble also spied two small satellites, named Mab and Cupid.

This Hubble Space Telescope snapshot of the dynamic blue-green planet Neptune

Hubble Finds New Neptune Moon

Astronomers used 150 of Hubble’s archival Neptune images taken from 2004 to 2009 to find the new moon.

Hubble Science Highlights

Discover the breadth and depth of Hubble's exciting discoveries!

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animation of a binary asteroid with a shifting tail

Tracking Evolution in the Asteroid Belt

These conglomerates of rock and ice may hold clues to the early solar system.

Three views of Pluto. Three mottled circles in colors of yellow, grey, rusty-orange, and black.

Uncovering Icy Objects in the Kuiper Belt

Hubble’s discoveries helped NASA plan the New Horizon spacecraft’s flyby of Pluto and beyond.

The Mystic Mountain is seen as a chaotic pillar of colorful gas and dust, narrowing toward the top of the image. The dust and gas is mostly yellow, brown, and orange, all jutting against a hazy purple and blue background with a few pink stars.

Exploring the Birth of Stars

Seeing ultraviolet, visible, and near-infrared light helps Hubble uncover the mysteries of star formation.

Hubble image of the Crab Nebula

The Death Throes of Stars

When stars die, they throw off their outer layers, creating the clouds that birth new stars.

Thirty proplyds in a 6 by 5 grid. Each one is unique. Some look like tadpoles, others like bright points in a cloudy disk.

Finding Planetary Construction Zones

Hubble’s sensitivity uncovers the seeds of planets in enormous disks of gas and dust around stars.

Artist's impression of the ten hot Jupiter exoplanets. Two rows of exoplanet illustrations. There are 5 planets of varying sizes, colors, and atmospheric features in each row.

Recognizing Worlds Beyond Our Sun

Hubble can detect and measure the basic organic components for life on planets orbiting other stars

Hubble view of an expanding halo of light around star v838 monocerotis

Seeing Light Echoes

Like ripples on a pond, pulses of light reverberate through cosmic clouds forming echoes of light.

Hubble Ultra Deep Field image

Tracing the Growth of Galaxies

Hubble’s Deep Field observations are instrumental in tracing the growth of galaxies.

Comma shaped curved cloud of gases in bright white edged with bright-pink star forming regions, and threaded with rusty-brown tendrils of dust at center and throughout the comma shaped merger. All set against the black of deep space.

Galaxy Details and Mergers

Galaxies evolve through gravitational interaction with their neighbors, creating a menagerie of forms.

Computer simulation of a supermassive black hole at the core of a galaxy. Center is a black circle. Surrounding the black circle are arcs of red, blue, orange, and white. Further out from the circle are blotches of red, blue, orange, and white representing celestial objects.

Monster Black Holes are Everywhere

Supermassive black holes lie at the heart of nearly every galaxy.

Six Hubble images in a grid of three across and two down. Each is a gamma-ray burst in a host galaxy. The images are orange-red and white with hints of yellow.

Homing in on Cosmic Explosions

Hubble helps astronomers better understand and define some of the largest explosions in the universe.

Cepheid star in Andromeda galaxy (Hubble observations)

Discovering the Runaway Universe

Our cosmos is growing, and that expansion rate is accelerating.

A field of galaxies along with the curved arcs of gravitationally lensed galaxies.

Focusing in on Gravitational Lenses

Gravitational lenses are ‘Nature’s Boost’, expanding our view deeper into space and farther back in time.

A cluster of galaxies fills the frame. A purple glow around the largest concentrations of galaxies indicates the distribution of dark matter.

Shining a Light on Dark Matter

The gravitational pull of dark matter guides the formation of everything we can see in the universe.

Top: Three views going back in time show slices of the cosmos. Bottom: A computer simulated, 3-D map of the distribution of dark matter.

Mapping the Cosmic Web

Filaments and sheets of matter create an interconnected web that forms the large-scale structure of the universe.