James Webb Space Telescope image of NGC 3324
Credit: NASA/ESA/CSA/STScI

The first images from the James Webb Space Telescope have arrived! They are starry, stellar, and dazzling images of never before seen nebulae and star-forming regions of the universe. The images are quite the upgrade from the images taken by the Hubble Space Telescope, showing deep space in exquisite detail. U.S. President Joe Biden released the first images on Monday, June 11, 2022.

The James Webb Space Telescope was successfully launched into space atop an Ariane 5 rocket on Dec. 25, 2021. The James Webb Space Telescope, abbreviated JWST, is an observatory replacing some capabilities of the Hubble Space Telescope. The Hubble Space Telescope is a powerful orbiting telescope that provides sharp images of heavenly bodies. Webb’s main mirror is 6.5 meters (21 feet) across. Webb will have about seven times larger light-collecting area than Hubble. However, Webb is designed to study infrared light, a type of light wave with longer wavelengths than those of visible light. Thus, Webb will not replace Hubble’s visible light capabilities.

Webb is a collaboration between the National Aeronautics and Space Administration (NASA), the European Space Agency (ESA), and the Canadian Space Agency (CSA). The Space Telescope Science Institute, which currently operates Hubble, is managing Webb’s science operations. The telescope is named after James Webb, the former NASA administrator who conceived and directed the Apollo program for most of the 1960’s. Webb has been a work in progress since 1996 and its deployment was delayed many times over the years.

The Webb telescope will enable scientists to study the history of the universe, nearly all the way back to a cosmic explosion called the big bang. It will collect information on the first stars and galaxies that formed after the big bang, the formation of planetary systems, and the evolution of planets within the solar system.

Southern Ring Nebula
Credit: NASA/ESA/CSA/STScI

The first images NASA released show a star-forming region in the Milky Way called the Carina Nebula captured in infrared light. A nebula is a cloud of dust particles and gases in space. The term nebula comes from the Latin word for cloud. Other images show the Southern Ring Nebula in near-infrared light and mid-infrared light. This image shows the remains of a white dwarf star, similar to our Sun.

Webb is equipped with several specialized cameras and spectrometers, instruments that spread out light into a band of wavelengths called a spectrum. Astronomers can study such a spectrum for signs of light given off by certain molecules or atoms. Webb also has a primary (main) mirror made of many segments, which was folded up to fit in the launch rocket. The mirror is to unfold and adjust to its proper shape before Webb reaches its permanent orbit. A large sun shield, about the size of a tennis court, will help prevent the infrared light from the sun, and the reflected sunlight from Earth and the moon, from interfering with observations. Webb is specifically designed to cool down its sensors to gather better data.

After launch, Webb traveled to a Lagrange point, a special point in space where the gravitational pulls of the sun and Earth are in balance. Webb is to remain there, 930,000 miles (1.5 million kilometers) from Earth, observing the skies for up to 10 years. During its primary mission, Webb is designed to be the world’s premier space observatory, used by thousands of astronomers worldwide.

August 9, 2018

Astronomers at the Carnegie Institution for Science in Washington, D.C., recently discovered a new batch of moons orbiting Jupiter, the largest planet in our solar system. The new group of 12 moons—which bring’s Jupiter’s moon total to an astounding 79—includes an oddball, however: one is going “the wrong way.”

Ganymede is the largest of Jupiter’s moons. Astronomers recently found 12 new and much smaller moons orbiting Jupiter, bringing the planet’s solar system-leading total to 79. Credit: NASA

Led by astronomer Scott Sheppard, the Carnegie team had been looking for “Planet Nine,” a hypothetical major planet in the Kuiper belt, a band of objects in the outer regions of our solar system. In March 2017, Jupiter moved into the astronomers’ search area. The telescope the team was using was uniquely suited for finding small or faraway objects: it could block out light from larger nearby heavenly bodies. Sheppard took time away from Planet Nine to poke around Jupiter, and his curiosity was rewarded with the discovery of 12 new moons. The first two bodies orbit close to Jupiter, and were quickly confirmed as moons. The other 10 skew farther out from the mighty planet and were not announced as moons until July 17, 2018.

Callisto, another large moon of Jupiter, has a diameter of almost 3,000 miles (4,800 kilometers), many times the size of Jupter’s newly discovered moons. Credit: NASA

The new moons are small, some less than a mile (several hundred meters) in diameter. Their orbital characteristics tell scientists a lot about them. Nine of the 10 newest moons orbit in retrograde, meaning in the opposite direction of the rotation of Jupiter. This leads the astronomers to think they formed from objects captured by Jupiter’s hefty gravitational pull. Most moons form with their parent planet and have prograde orbits, meaning they orbit in the same direction as the host planet. But captured objects often have retrograde orbits. Sheppard’s team thinks these nine moons are parts of captured objects broken up by collisions over millions or billions of years.

The tenth of the newest moons, however—which Sheppard calls Valetudo, a great-granddaughter of the Roman mythological god Jupiter—travels in a prograde orbit. It dives through the orbits of the other nine moons, putting it on an eventual collision course. When moon finally meets moon, the impact will either destroy the bodies or make them even smaller.

January 4, 2018

Astronomers at the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) observatory at the summit of the dormant volcano Haleakala in Hawaii recently detected a mysterious object speeding through our solar system. This by itself was not unusual. One of the main missions of the Pan-STARRS project is to detect near-Earth objects in space that could possibly collide with our planet. However, researchers quickly realized that this space rock did not move like the asteroids and comets they routinely encounter. Astronomers quickly learned that this object was a visitor from beyond our solar system—the first interstellar asteroid ever observed.

This artist’s impression shows `Oumuamua the interstellar asteroid. Credit: ESO/M. Kornmesser

Scientists at NASA’s Center for Near-Earth Object Studies (CNEOS) in Pasadena, California, determined the object was an asteroid, now officially designated as A/2017 UI. Its composition and its unusual path through our solar system showed it was from outer space. Researchers at Pan-STARRS named the asteroid `Oumuamua, which is a Hawaiian word that means messenger.

`Oumuamua appeared only as a faint spot on the Pan-STARRS telescope as it zipped through our solar system at up to 196,000 miles per hour (355,431 kilometers per hour). But later images from other observatories showed that `Oumuamua was 1,300 feet (400 meters) long and about 10 times as long as it was wide, and spinning rapidly. `Oumuamua’s elongated cigar shape is a rarity among space objects. Most asteroids are compact and lumpy after having been battered by countless random collisions with other objects on their long journeys through space. `Oumuamua is also dark red, a color created as its rocky surface was bombarded by high-energy cosmic rays for millions or perhaps billions of years. A/2017 UI traveled in a retrograde orbit (opposite that of the planets) around the sun on its way toward the constellation Pegasus.

Some researchers suggested that `Oumuamua was more than just an interstellar oddity, and that it was perhaps a message from a distant alien civilization. They pointed out that “a cigar or needle shape is the most likely architecture for an interstellar spacecraft, since this would minimize friction and damage from interstellar gas and dust.” Several groups scanned `Oumuamua for alien radio transmissions, including researchers at the Green Bank Telescope in West Virginia, the William Herschel Telescope in Spain’s Canary Islands, and the European Southern Observatory’s Very Large Telescope in Chile. No alien messages were found, and the consensus was that `Oumuamua was odd but completely natural. Scientists suspect that the so-called “space cucumber” has an icy core—as do most comets—beneath its hard carbonic shell.

March 1, 2017

On February 22, astronomers announced the discovery of a remarkable planetary system orbiting a relatively nearby star. Planets outside the solar system are called extrasolar planets or exoplanets. The new system has a whopping seven planets, many of which might host conditions favorable for life. The finding was published in the journal Nature.

This artist’s concept shows what each of the TRAPPIST-1 planets may look like, based on available data about their sizes, masses and orbital distances.
Credit: NASA/JPL-Caltech

The system is located some 40 light-years away in the constellation Aquarius, the Water Bearer. One light-year is the distance that light travels in a vacuum in a year, about 5.88 trillion miles (9.46 trillion kilometers). The planets orbit a star called TRAPPIST-1, named in honor of the telescope used in the discovery. TRAPPIST stands for Transiting Planets and Planetesimals Small Telescope. It is a robotic telescope in Chile funded by Belgium. In May 2016, TRAPPIST detected three planets orbiting a type of small, relatively cool star called a red dwarf. In September, the Spitzer Space Telescope, operated by the United States National Aeronautics and Space Administration (NASA), began monitoring the system. With the help of NASA’s Hubble Space Telescope and other ground-based telescope systems, Spitzer confirmed the existence of two of the planets. But Spitzer determined that the third signal detected by TRAPPIST actually came from four planets, not one. Later, the telescope observed traces of a seventh, even more distant, exoplanet.

Even this farthest exoplanet orbits closer to TRAPPIST-1 than Mercury does to the sun, at a distance of only about 5.6 million miles (9.0 million kilometers). For comparison, Earth orbits about 93 million miles (150 million kilometers) from the sun. Because red dwarfs are much smaller and cooler than the sun, however, three of the planets orbit within a region that should be neither too hot nor too cold for liquid water to exist on their surfaces. Most scientists consider liquid water essential for life, so such a region around a star is known as its habitable zone.

The planetary system’s compact size would provide spectacular views only imagined in science fiction. The star TRAPPIST-1 would appear three times as large as the sun does on Earth, bathing the planets with a dim, pinkish light. Because the exoplanets are so close together, an observer standing on one planet could clearly see the other six. Neighboring planets would sometimes appear larger than does the moon in Earth’s sky.

Follow-up studies are already underway. NASA’s renowned planet-hunting satellite Kepler is currently examining the system. All seven planets are about the size of Earth, but Kepler will more precisely calculate their sizes and possibly find more planets. Spitzer has already confirmed that two of the planets are rocky worlds, rather than gaseous planets like Neptune. But Spitzer will continue to examine the system to learn more about the planets’ masses and compositions. In 2018, NASA plans to launch the James Webb Space Telescope. This powerful satellite should be able to detect if any of the exoplanets have atmospheres and determine their compositions. If the atmosphere contains compounds such as methane, oxygen, and ozone, it would be a strong indication that life exists there.

Other Behind the Headlines posts:

• Ten to 30 Alien Planets for Every Person on Earth? (Jan. 13, 2012)
• Amateur Astronomers Discover a Planet with Four Suns (Oct. 17, 2012)
• New Exoplanet Candidates from Ailing Kepler Spacecraft (June 20, 2013)
• Kepler Space Telescope Goes Dark–For Now (Aug. 16, 2013)
• Exoplanet Bonanza from Kepler (Feb. 27, 2014)
• First “Earth-Cousin” Found by Kepler Space Telescope (May 1, 2014)
• “Hello, Aliens? Are You Out There?” (Feb. 13, 2015)
• New Planetary Neighbors (May 11, 2016)
• The Pale Red Dot: Proxima b (Aug. 31, 2016)
  

This artist’s rendering shows a view of Planet Nine from a perspective facing towards the distant sun. The planet is thought to be gaseous, similar to Uranus and Neptune. Credit: Caltech/R. Hurt (IPAC)

January 22, 2016

On Wednesday, January 20, astronomers Konstantin Batygin and Mike Brown from the California Institute of Technology (Caltech) in Pasadena released a study in The Astronomical Journal suggesting that there may be a ninth planet in the solar system after all. But it isn’t the dwarf planet Pluto, or Eris—or any other tiny, frozen ball of rock, for that matter.

Batygin and Brown analyzed the orbits of six objects with elongated orbits in the Kuiper belt. They noticed that all of these objects orbited the sun in a distinctive way, with their perihelia (the part of an orbit closest to the sun) clustered on one side of the solar system. Using computer simulations, the astronomers suggest that a ninth planet with about 10 times the mass of Earth is causing the orbits of the Kuiper belt objects to cluster in this way.

Predicting the existence of large objects on the edge of our solar system is not a new venture. After Uranus was discovered in 1781, astronomers noted that it was not orbiting exactly as it should, a hint that another large planet was altering its orbit. In 1846, French mathematician Urbain J. J. Le Verrier calculated the orbit of this outer planet and predicted its location in the night sky. Astronomers found the planet—now called Neptune—almost exactly where Le Verrier predicted.

Neptune’s discovery is the only successful prediction of this type to date. Around 1900, American businessman and amateur astronomer Percival Lowell became convinced that a ninth planet lurked beyond Neptune, based on more apparent inconsistencies in Uranus’s orbit. Clyde Tombaugh eventually discovered Pluto using the giant observatory in Flagstaff, Arizona, which Lowell built to look for Planet X. Pluto, however, was far too small to affect the orbit of Uranus. Much later, observations by space probes refined the values for Uranus’s size and mass. These values showed there was no problem with the planet’s orbit after all.

Although the evidence is strong, scientists will have to see Planet Nine to believe it. The planet will be extremely difficult to locate by telescope, despite its apparently large size. It is incredibly far away, from 600 to 1,200 times farther than is the sun from the Earth. Planet Nine completes an orbit every 15,000 years. For comparison, Pluto, the former ninth planet, is only about 40 times farther from the sun than Earth is and it completes an orbit every 248 years. It might take as long as five years of scientists combing the night sky with powerful telescopes to find Planet Nine. Until then, the solar system will have eight planets.

November 26, 2014

A remastered image of Jupiter’s moon Europa released by NASA shows, for the first time, how this ice-covered body would appear to the human eye. The image is actually a mosaic of images taken by the Galileo spacecraft in the late 1990′s. The previous version of the image had been strongly enhanced with false color. The new image shows Europa in near-natural color.

Areas of Europa’s surface that appear blue or white contain relatively pure water ice. Reddish and brownish areas include higher amounts of other gases or solids. The polar regions, which are visible at the left and right of the image, are much bluer than the more equatorial latitudes. Scientists suspect this difference is due to differences in the size of the ice grains in these locations. (NASA/JPL-Caltech/SETI Institute)

Although Europa is one of the smoothest bodies in the solar system, its surface features include shallow cracks, valleys, ridges, pits, blisters, and icy flows. However, none of them extend more than a few hundred yards or meters upward or downward. In some places, huge sections of the surface have split apart and separated. The surface of Europa has few impact craters (pits caused by collisions with asteroids or comets). The splitting and shifting of the surface and disruptions from below have destroyed most of the old craters.

Europa is considered one of the likeliest places in the solar system for the existence of extraterrestrial life. Beneath its icy surface is an immense lake of salty liquid water that might be a home for living things.

March 28, 2014

A probable dwarf planet that orbits much farther from the sun than any other known object has been discovered by American astronomers Chad Trujillo and Scott Sheppard. The little planet is so far away that its orbit takes it 15 times as far from the sun as the orbit of Neptune, the most distant major planet in the solar system. The astronomers first sighted the object, designated 2012 VP113, or VP for short, using the Dark Energy Camera mounted on the 4-meter Blanco telescope in Chile. However, to confirm the shape of the object’s orbit around the sun, the astronomers needed to watch the object for many months. The would-be dwarf planet VP is the second such object found orbiting the sun at such a vast distance. The first, named Sedna, was discovered in 2003 by a team that included Trujillo. VP appears to be about 280 miles (450 kilometers) across, about half the size of Sedna and the most commonly known dwarf planet, Pluto. Trujillo and Sheppard nicknamed the new dwarf planet Biden, for United States Vice President Joe Biden.

The distance from Earth to the sun is, on average, about 93 million miles (150 million kilometers). This distance is called an astronomical unit or AU. Neptune is about 30 AU from the sun. The orbit of Sedna is a stretched out oval that carries it as far as 1,000 AU from the sun. However, Sedna also comes to within 76 AU of the sun at its closest approach. The orbit of VP is more circular. For this reason, VP doesn’t stray as far as Sedna, only about 450 AU. On the other hand, VP never gets closer than 80 AU to the sun at its closest approach, farther than any other solar system body known.

Dwarf planets Ceres, Eris, Haumea, Makemake, and Pluto and their moons, compared with Earth and its moon. All of these dwarf planets are smaller than the moon. (©UCAR/University of Michigan)

The area to which Pluto and several other dwarf planets belong is called the Kuiper belt. It is the region beyond Neptune and includes millions of icy bodies. Far beyond the Kuiper belt is a region called the Oort cloud, an area thought to be filled with millions of comets. Both Sedna and VP orbit between the Kuiper belt and the Oort cloud. Many astronomers believed this area was empty. The discovery of Sedna and now VP puts that idea into question.

The discovery offers new information about how the solar system was formed. How did such large objects assume orbits so far from the sun? How many are there yet to be found? One interesting conclusion suggested by astronomers studying the new data is that the orbits of Sedna and VP may be influenced by a large, yet undiscovered planet.

Additional World Book articles:

• Ceres
• Eris
• Planet (the dwarf planets)
• Exploring the Suburban Solar System (a Special Report)
• Astronomy (2004) (a Back in Time article)
• Astronomy (2006) (a Back in Time article)

February 27, 2014

The number of known exoplanets in the Milky Way Galaxy has nearly doubled, thanks to a new method of confirming planet candidates discovered by the Kepler space telescope. Mission control officials at NASA‘s Ames Research Center in Moffett Field, California, announced that they had identified 715 new planets, which raises the total number of alien planets to some 1,700. The research has also significantly increased the number of smaller exoplanets. About 95 percent of the new planets are smaller than Neptune, which is about 17 times as massive as Earth. Many exoplanets found previously were at least as massive as Jupiter, which is 318 times as massive as Earth. All of the newly discovered planets orbit one of 305 stars in a multiplanet system like the solar system.

Although Kepler’s original planet-hunting days are over–the telescope has been nonoperational since May 2013–mission scientists are still on the job. The new exoplanets were found in data collected during the telescope’s first two years in orbit, from 2009 to 2011. Kepler’s main mission was to search one section of the Milky Way for Earth-like planets in the “habitable zone.” The habitable zone, also called the Goldilocks zone, is the region around a star that scientists believe is neither too hot nor too cold to support life as we know it. In this zone, the temperature is cool enough to let liquid water form and warm enough to prevent water from freezing. Earth orbits in the habitable zone of the solar system. Although Kepler searched over 150,000 stars for signs of orbiting planets, its search zone was actually quite small. Scientists estimate that the Milky Way alone has up to 200 billion stars.

All of the newly identified planets orbit a star in a multiplanet system, like the solar system. (NASA)

The new method of identifying planets is called validation by multiplicity. This method, which relies on the logic of probability, allows scientists to identify exoplanets in groups, rather than one by one. NASA officials compared the technique to the behavior of lions and lionesses living on the savannah. “In our imaginary savannah, the lions are the Kepler stars and the lionesses are the planet candidates,” the agency explained in a press release. “If you see two of the big cats it could be a lion (star) and a lioness (planet) or two lions. But if more than two large felines are gathered, then it is very likely to be a lion and his pride (star and its planets).”

Additional World Book articles:

• Binary star
• In Search of Other Worlds (a special report)
• Space exploration (2011) (a Back in Time article)

February 14, 2014

The wildly complicated surface of Ganymede, the largest moon in the solar system, appears in colorful detail in a new map published by the United States Geological Survey. The map is based on images taken by NASA’s Voyager 1 and Voyager 2 spacecraft, which flew by Jupiter and its moons in 1979, and the Galileo probe, which orbited Jupiter from 1995 to 2003. The map is the first global geologic map of Ganymede, Jupiter’s seventh moon, or any other icy moon, for that matter.

Ganymede, also Jupiter’s largest moon, is bigger than the planet Mercury and almost as large as Mars. Ganymede is one of four Jovian moons discovered by the Italian scientist Galileo Galilei in 1610. From observations using Earth-based telescopes and orbiting spacecraft, scientists have long known that Ganymede’s icy surface is made up of almost equal amounts of dark and light material. A thin ocean of salty water may lay about 105 miles (170 kilometers) below the surface. The presence of water makes Ganymede and the other large moons of Jupiter—along with Mars—prime candidates in the search for extraterrestrial life.

The false colors in a new map of Ganymede reveal geologic features created during different times in the moon's history. (USGS Astrogeology Science Center/Wheaton/NASA/JPL-Caltech)

The new false-color map, which was created by a team of scientists headed by Geoffrey Collins of Wheaton College in Massachusetts, provides the first solid evidence for three major geological periods in the moon’s history. During the oldest period, represented in brown, asteroids and comets bombarded the surface, leaving many impact craters. Forces released by the biggest impacts also created large cracks in the moon’s crust. Lighter colors on the map represent two somewhat younger periods. During one of these, changes in the temperature of the moon caused the surface to expand and crack. The new terrain (land) created by these tectonic forces was marked with parallel sets of ridges and valleys. During the third period, geologic activity declined. As the crust settled, new ridges and valleys appeared.

Additional articles in World Book:

• Callisto
• Europa
• Io
• Satellite (Satellites of the gas giants)
• Probing the Planets (a Special Report)
• The Thirty-Year Journey of Voyagers 1 & 2 (a Special Report)

October 2, 2013

After an amazing 35-year trek, the Voyager 1 spacecraft has crossed the threshold of a vast region of space called the heliosphere, scientists at NASA’s Jet Propulsion Laboratory (JPL) have announced. Did the little craft that just keeps going also exit the solar system? The answer is: not really, despite many reports in news media. Nevertheless, Voyager’s accomplishment is still a big deal.

The heliosphere is a teardrop-shaped region of space that holds the sun and all the planets. The heliosphere is created by the solar wind–a stream of electrically charged gas particles given off by the sun. The sun and the heliosphere are traveling together through interstellar space (the space between the stars), like an air bubble through water. So by leaving the heliosphere, Voyager 1 has gone where no human-made object has gone before–to interstellar space. JPL scientists said this milestone occurred on about August 25, 2012, when Voyager was about 11.5 billion miles (18.5 billion kilometers) from Earth.

But Voyager 1 has not really left the solar system. That’s because the solar system also includes a large band of objects even farther out in space called the Oort cloud. The Oort cloud, which is held by the gravity of the sun, begins about 500 billion miles (800 billion kilometers) from the sun.

The scale bar in the illustration is measured in astronomical units (AU's). Each AU equals the distance from the sun to the Earth. (NASA/JPL-Caltech)

Because the Oort cloud orbits the sun, it is in the solar system. But it is also in interstellar space. Why is that? In short, most scientists believe that the edge of the heliosphere and the edge of the solar system are not the same. The pressure of the solar wind decreases as it speeds through space because the charged particles spread out. At the edge of the heliosphere, the pressure of the solar wind equals the pressure from the interstellar medium (the charged particles streaming through interstellar space). The density of these charged particles is different from those in the solar wind. This difference enabled scientists to determine when and where Voyager 1 crossed into interstellar space.

To actually leave the solar system, Voyager 1 would still need to cross the Oort cloud. Assuming the spacecraft survives, it would take another 200 to 300 years to even reach the Oort cloud and about another 30,000 years to exit the far side, the most commonly recognized edge of the solar system. If Voyager makes it this far, we will probably never know. Voyager 1 is expected to run out of nuclear fuel and to cease collecting data and communicating with Earth in the mid-2020′s.

Launched in 1977, Voyager 1 and Voyager 2 have lasted longer and traveled farther than any other space probes in history. Voyager 2 is now about 9.5 billion miles (15.3 billion kilometers) from the sun, going in the opposite direction from Voyager 1.

The two Voyager spacecraft explore the outer edges of the heliosphere, a vast, tear-drop-shaped region of space that contains the sun and planets, in an artist's illustration. Voyager 1 has now left the heliosphere. (NASA/JPL-Caltech)

Additional information:

• Listen to a recording of the sounds of charged particles vibrating in interstellar space made by Voyager 1 here.
• The Voyager site at the Jet Propulsion Laboratory
• The Voyager site at NASA

Additional World Book articles:

• Space exploration
• The Thirty-Year Journey of Voyagers 1 & 2 (A Special Report)
• Astronomy (1979) (A Back in Time article)
• Astronomy (1989) (A Back in Time article)
• Space Exploration (1977) (A Back in Time article)
• Space Exploration (1979) (A Back in Time article)