My Science School

Humans have not set foot on the moon for nearly 50 years, but the Apollo moon missions aren’t over. The echoes from Neil Armstrong’s first steps are still helping scientists make giant leaps in understanding the moon’s geology.

When Apollo 17 packed up for home in 1972, the astronauts brought rock samples with them. NASA locked many of the rocks and core samples away in a vault, awaiting technological innovations that would allow future scientists to study them better than 1970s technology allowed.

Now, Purdue University scientists including Michelle Thompson, an assistant professor of Earth, Atmospheric and Planetary Sciences in Purdue’s College of Science, and Marc Caffee, professor of physics and astronomy with a courtesy appointment in the Department of Earth, Atmospheric, and Planetary Sciences, are both working on teams that will analyze some of the moon rocks and lunar soil samples from that mission.

Thompson and her team are partnering with some of the original scientists, including Harrison “Jack” Schmitt, the first and only geologist ever to walk on the moon, to learn more about the moon itself through the rock samples.

Credit : Purdue 

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Our Milky Way galaxy is a big place. Even at this blazing speed, it takes the sun approximately 225-250 million years to complete one journey around the galaxy’s center.

This amount of time – the time it takes us to orbit the center of the galaxy – is sometimes called a cosmic year.

By the way, in the past when we’ve talked about this subject, people have commented on the difference between the words rotate and revolve. The word revolve means to orbit around another body. Earth revolves (or orbits) around the sun. The sun revolves around the center of the Milky Way galaxy.

On the other hand, rotate means to spin on an axis. The Earth rotates every 24 hours. The sun rotates, but not at a single rate across its surface. The movements of the sunspots indicate that the sun rotates once every 27 days at its equator, but only once in 31 days at its poles.

The planets in our solar system orbit (revolve) around the sun, and the sun orbits (revolves) around the center of the Milky Way galaxy. We take about 225-250 million years to revolve once around the galaxy’s center. This length of time is called a cosmic year.

Credit : Earth Sky 

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Jupiter is the fastest spinning planet in our Solar System rotating on average once in just under 10 hours. That is very fast especially considering how large Jupiter is. This means that Jupiter has the shortest days of all the planets in the Solar System. 

Jupiter is the 5th planet from the sun and it is the biggest of all planets in the solar system. It is a giant gaseous planet and about 2.5 times the size of all planets combined in the solar system. It spins on its axis in the opposite direction as opposed to most planets. Other gas planets include Saturn, Uranus, and Neptune. Jupiter is believed to have a solid core made of rocks. Like most other planets, Jupiter does not have a defined solid surface. As a result of its rotation, the planet has an oblate spheroid shape having a bulge along the equator. The atmosphere of the planet is divided into different bands that vary with the altitude. At the boundaries are great turbulence and storms and the popular one is the Great Red Spot; a giant storm, which was first observed in the 17th century using a telescope. Because the surface of the planet is not solid, the rotational speed around the equator is different from that of its polar areas, and this is why it has a bulge at its equator. The rotational speed at the equator of this planet is 28,273 miles per hour. A complete day in Jupiter around the poles is an estimated nine hours and 56 minutes while at the equator it is an estimated nine hours and 50 minutes.

Jupiter is made up of 92% hydrogen and 8% of helium in the volume by gas composition, while by mass, its atmosphere is comprised of about of 75% hydrogen and 25% helium. In comparison to the planet Earth, Jupiter is massive but has low density. Jupiter has three rings around it and other moons, which orbit around it as well. The planet has faint narrow rings, which are dark and made of dust and rock fragments. Unlike the rings of Saturn, the rings of Jupiter are constantly losing materials and being replenished with the dust from other tiny meteors hitting the four inner moons. Jupiter has about 69 moons, which include four large moons that were discovered in 1610 by Galileo and they are known as Galilean moons. The largest of the four moons is the Ganymede, which has a larger diameter than planet Mercury. The Jupiter’s rings have three sections namely halo, main, and Gossamer rings.

Credit : World Atlas 

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Moons — also called natural satellites — come in many shapes, sizes and types. They are generally solid bodies, and few have atmospheres. Most planetary moons probably formed from the discs of gas and dust circulating around planets in the early solar system.

Earth's Moon probably formed when a large body about the size of Mars collided with Earth, ejecting a lot of material from our planet into orbit. Debris from the early Earth and the impacting body accumulated to form the Moon approximately 4.5 billion years ago (the age of the oldest collected lunar rocks). Twelve American astronauts landed on the Moon during NASA's Apollo program from 1969 to 1972, studying the Moon and bringing back rock samples.

Usually the term moon brings to mind a spherical object, like Earth's Moon. The two moons of Mars, Phobos and Deimos, are different. While both have nearly circular orbits and travel close to the plane of the planet's equator, they are lumpy and dark. Phobos is slowly drawing closer to Mars and could crash into the planet in 40 or 50 million years. Or the planet's gravity might break Phobos apart, creating a thin ring around Mars.

Credit : NASA Science 

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China and Russia have agreed to jointly build a research station on or around the moon, setting the stage for a new space race.

The United States and the Soviet Union, followed by its successor state, Russia, have long dominated space exploration, putting the first astronauts in space and on the moon and later collaborating on the International Space Station that has been in orbit for two decades.

The joint announcement by China and Russia on Tuesday has the potential to scramble the geopolitics of space exploration, once again setting up competing programs and goals for the scientific and, potentially, commercial exploitation of the moon. This time, though, the main players will be the United States and China, with Russia as a supporting player.

In recent years, China has made huge advances in space exploration, putting its own astronauts in orbit and sending probes to the moon and to Mars. It has effectively drafted Russia as a partner in missions that it has already planned, outpacing a Russian program that has stalled in recent years.

Credit : The New York Times 

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 In 2000, Chawla was selected for her second voyage into space, serving again as a mission specialist on STS-107. The mission was delayed several times, and finally launched in 2003. Over the course of the 16-day flight, the crew completed more than 80 experiments.

On the morning of Feb. 1, 2003, the space shuttle returned to Earth, intending to land at Kennedy Space Center. At launch, a briefcase-sized piece of insulation had broken off and damaged the thermal protection system of the shuttle's wing, the shield that protects it from heat during re-entry. As the shuttle passed through the atmosphere, hot gas streaming into the wing caused it to break up. 

The unstable craft rolled and bucked, pitching the astronauts about. Less than a minute passed before the ship depressurized, killing the crew. The shuttle broke up over Texas and Louisiana before plunging into the ground. The accident was the second major disaster for the space shuttle program, following the 1986 explosion of the shuttle Challenger.

The entire crew of seven was killed. In addition to Chawla, the crew included: Rick Husband, Laurel Clark, Ilan Ramon, David Brown, William McCool and Michael Anderson.

Over the course of her two missions, Chawla logged 30 days, 14 hours, and 54 minutes in space. After her first launch, she said, "When you look at the stars and the galaxy, you feel that you are not just from any particular piece of land, but from the solar system."

Credit : Space.com 

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Most golfers really want to avoid sand traps, but NASA astronaut Alan Shepard had no choice but to deal with one when wielding a six-iron head on the moon's dusty surface 50 years ago this month.

Shepard took a few moments during the Apollo 14 landing to show off his hobby during a live broadcast from the lunar surface on Feb. 6, 1971. He took two shots, with the second ball going "miles and mile," he said on-camera. 

He was exaggerating, according to new analysis from the United States Golf Association (USGA). Based on data from the crew and a modern-day moon mission, the group found that the first ball traveled 24 yards (22 meters) and the second about 40 yards (37 m). By comparison, a 2019 report using golf tournaments' gender categories shows that an average amateur male golfer on Earth can drive the ball 216 yards (198 m), and an average female golfer 148 yards (135 m), although those distances have increased significantly since Shepard's flight. 

To be fair to Shepard, however, he had more obstacles to contend with than your typical Sunday hobbyist. His golf "club" was actually a modified sample collection device with the head attached to the end. He was also wearing a notoriously stiff spacesuit that forced him to swing with a single arm.

Credit : Space.com

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Astronaut, designation, derived from the Greek words for “star” and “sailor,” commonly applied to an individual who has flown in outer space. More specifically, “astronaut” refers to those from the United States, Canada, Europe, and Japan who travel into space. Those Soviet and later Russian individuals who travel into space are known as cosmonauts (from the Greek words for “universe” and “sailor”). China designates its space travelers taikonauts (from the Chinese word for “space” and the Greek word for “sailor”).

Even though initially most U.S. astronauts were test pilots, this requirement had more to do with their ability to perform effectively in high-stress situations than with their piloting skills, since the spacecraft used in the Mercury, Gemini, and Apollo programs had limited maneuvering capability in orbit and came back to Earth using parachutes for reentry. Beginning in 1978, with the advent of the space shuttle, which functioned as a laboratory and operations centre when in orbit and then as a high-speed, difficult-to-control glider as it reentered the atmosphere and flew to a runway landing, the National Aeronautics and Space Administration (NASA) selected two types of individuals as astronaut candidates. One group was required to have extensive flying experience in jet aircraft. These astronaut candidates were trained to serve as shuttle pilots and eventually shuttle mission commanders. The second group was chosen to become mission specialist astronauts. These candidates were not required to be pilots (though some were); rather, they were individuals with advanced scientific, medical, or engineering training or experience. Beginning in 1992, in anticipation of participating in missions to the International Space Station (ISS), a number of individuals from various countries became international mission specialist astronaut candidates.

Mission specialists were trained to have primary responsibility during a mission for operating shuttle or space station systems and carrying out payload and experimental activities. Mission specialists also performed extravehicular activities (space walks).

Credit : Britannica 

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The first woman to travel in space was Soviet cosmonaut, Valentina Tereshkova. On 16 June 1963, Tereshkova was launched on a solo mission aboard the spacecraft Vostok 6. She spent more than 70 hours orbiting the Earth, two years after Yuri Gagarin’s first human-crewed flight in space.

Tereshkova was born on 6 March 1937 in the village of Bolshoye Maslennikovo in central Russia. Her mother was a textile worker, and her father was a tractor driver who was later recognised as a war hero during World War Two. At the time of his death on the Finnish front, Tereshkova was only two years old. 

After leaving school, Tereshkova followed her mother into work at a textile factory. Her first appreciation of flying was going down rather than up when she joined a local skydiving and parachutist club. It was her hobby of jumping out of planes that appealed to the Soviets' space programme committee. On applying to the cosmonaut corps, Tereshkova was eventually chosen from more than 400 other candidates. 

Tereshkova received 18 months of severe training with the Soviet Air Force after her selection. These tests studied her abilities to cope physically under the extremes of gravity, as well as handle challenges such as emergency management and the isolation of being in space alone. At 24 years old, she was honourably inducted into the Soviet Air Force. Tereshkova still holds the title as the youngest woman, and the first civilian to fly in space. 

While Tereshkova remains the only woman to have flown solo in space, her mission was a dual flight. Fellow cosmonaut Valeriy Bykovsky launched on Vostok 5 on 14 June 1963. Two days later, Tereshkova launched. The two spacecraft took different flight paths and came within three miles of each other. The cosmonauts exchanged communications while making 48 orbits of Earth, with Tereshkova responding to Bykovsky via her callsign ‘Seagull’. During the flight, the Soviet state television network broadcast a video of Tereshkova inside the capsule, and she spoke with the Russian Premier Nikita Khrushchev over the radio. 

In her later life, Tereshkova was decorated with prestigious medals and has held several prominent political positions both for the Russian and global councils. Before the collapse of the Soviet Union, she was an official head of State and was elected a member of the World Peace Council in 1966. 

Today, she holds the position of Deputy Chair for the Committee for International Affairs in Russia. She also remains active within the space community and is quoted as suggesting that she would like to fly to Mars - even if it were a one-way trip. 

Credit : Royal Museums Greenwich 

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Guion "Guy" Bluford is a former NASA astronaut who was the first African-American to fly into space. He flew four shuttle missions.

Bluford's class of astronauts from 1978 included two other African-Americans: Ron McNair (who later died on the space shuttle Challenger in 1986) and Fred Gregory (who after flying in space, went on to become a NASA deputy administrator.)

"All of us knew that one of us would eventually step into that role," Bluford later told NASA about being the first. "I probably told people that I would probably prefer not being in that role ... because I figured being the No. 2 guy would probably be a lot more fun."

In the next decade, Bluford would fly three more times as a mission specialist aboard NASA space shuttles. His next mission — STS-61A, also aboard Challenger, in late 1985 — was so packed with things to do that Bluford's shift often needed help from other crew members to fix meals. The eight crewmembers were doing the first Spacelab mission, which was partially run under the German Space Operations Center — another first for NASA.

"After the mission, [the Germans] invited us and our wives to Germany to attend a technical conference highlighting the results of our mission," Bluford recalled in a 2004 oral interview.

"It was a proud moment for all of us as we learned the results of some of the experiments that we performed during flight. The trip also gave me an opportunity to tour Europe with the wife and show her some of the sights that I had seen while training there."

Credit : Space.com 

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While Jupiter is known for its four large Galilean moons (so named because they were observed by Galileo with his 17th century telescope), Saturn has two moons that have drawn astronomers' attention: Enceladus and Titan.

Both Enceladus and Titan are ocean moons, meaning they have subsurface oceans of liquid water. Titan even has surface lakes, though these are composed of methane and ethane. Enceladus is an icy moon known for spraying huge plumes of water up through its atmosphere into space; during the Cassini mission, astronomers were able to sample these geysers and that's how they discovered the ocean underneath its icy crust.

Enceladus is named after a giant in Greek mythology.

Pictures from the Voyager spacecraft in the 1980s indicated that although this moon is small—only about 310 miles (500 kilometers) across — its icy surface is remarkably smooth in some places, and bright white all over. In fact, Enceladus is the most reflective body in the solar system. For decades, scientists didn’t know why.

Because Enceladus reflects so much sunlight, the surface temperature is extremely cold, about minus 330 degrees Fahrenheit (minus 201 degrees Celsius). But it is not as cold and inactive a place as it appears.

Titan is larger than the planet Mercury and is the second largest moon in our solar system. Jupiter's moon Ganymede is just a little bit larger (by about 2 percent). Titan’s atmosphere is made mostly of nitrogen, like Earth’s, but with a surface pressure 50 percent higher than Earth’s. Titan has clouds, rain, rivers, lakes and seas of liquid hydrocarbons like methane and ethane. The largest seas are hundreds of feet deep and hundreds of miles wide. Beneath Titan’s thick crust of water ice is more liquid—an ocean primarily of water rather than methane. Titan’s subsurface water could be a place to harbor life as we know it, while its surface lakes and seas of liquid hydrocarbons could conceivably harbor life that uses different chemistry than we’re used to—that is, life as we don’t yet know it. Titan could also be a lifeless world.

Credit : NASA Science 

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Ganymede is the largest moon in the solar system (larger than the planet Mercury), and is the only moon known to have its own internally generated magnetic field.

Ganymede is the only moon known to have its own magnetic field – a discovery made by NASA’s Galileo spacecraft in 1996. The magnetic field causes auroras, which are ribbons of glowing, hot, electrified gas, in regions circling the north and south poles of the moon. Because Ganymede is close to Jupiter, its magnetic field is embedded in, or lies within, Jupiter’s magnetic field.

When Jupiter’s magnetic field changes, the auroras on Ganymede also change, “rocking” back and forth. It was by watching the rocking motion of the two auroras, that a team of scientists led by Joachim Saur of the University of Cologne in Germany came up with the idea of using the Hubble space telescope to learn more about the inside of the moon.

Ganymede has two distinct types of terrain: large, bright regions of ridges, and grooves that slice across older, darker terrains. This suggests to scientists that Ganymede's crust has been under tension from global tectonic processes. NASA’s Juno spacecraft took the most recent images of Ganymede’s surface during flybys in June 2021.

Ganymede was discovered by Italian astronomer Galileo Galilei on Jan. 7, 1610. The discovery, along with his discovery of three other large moons around Jupiter, was the first time a moon was discovered orbiting a planet other than Earth. The discovery eventually led to the understanding that planets in our solar system orbit the Sun, instead of our solar system revolving around Earth. (Jupiter now has 53 named moons and 26 provisional moons awaiting confirmation of discovery).

Credit : NASA Science 

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Uranus’ moons are named after characters from the works of William Shakespeare and Alexander Pope.

To date 27 moons have been discovered around Uranus, those named after characters from Shakespeare include Titania (A Midsummer Night’s Dream), Oberon (A Midsummer Night’s Dream), Ariel (The Tempest), Miranda (The Tempest) and Puck (A Midsummer Night’s Dream).

Titania and Oberon were discovered in 1787 by William Herschel, Ariel in 1851 by William Lassell, Miranda in 1948 by Gerard Kuiper and Puck was discovered by the Voyager 2 spacecraft in 1985.

"Sweet Moon," William Shakespeare wrote in "A Midsummer Night's Dream," "I thank thee for thy sunny beams; I thank thee, Moon, for shining now so bright." Centuries later, the moons of Uranus pay homage to the famous playwright.

While most of the satellites orbiting other planets take their names from ancient mythologies, Uranus' moons are unique in being named for Shakespearean characters, along with a couple of the moons being named for characters from the works of Alexander Pope.

Oberon and Titania are the largest Uranian moons, and were first to be discovered—by William Herschel in 1787. William Lassell, who had been first to see a moon orbiting Neptune, discovered the next two, Ariel and Umbriel. Nearly a century passed before Gerard Kuiper found Miranda in 1948. And that was it until a NASA robot made it to distant Uranus.

The Voyager 2 spacecraft visited the Uranian system in 1986 and tripled the number of known moons. Voyager 2 found an additional 10, just 26-154 km (16-96 miles) in diameter: Juliet, Puck, Cordelia, Ophelia, Bianca, Desdemona, Portia, Rosalind, Cressida and Belinda.

Since then, astronomers using the Hubble Space Telescope and improved ground-based telescopes have raised the total to 27 known moons. Spotting the post-Voyager moons is an impressive feat. They're tiny—as little as 12-16 km (8-10 miles) across, and blacker than asphalt. And of course, they're about 2.9 billion km (1.8 billion miles) away from the Sun.

All of Uranus's inner moons (those observed by Voyager 2) appear to be roughly half water ice and half rock. The composition of the moons outside the orbit of Oberon remains unknown, but they are likely captured asteroids.

Credit : NASA Science 

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Phobos and Deimos bear more resemblance to asteroids than to Earth's moon. Both are tiny — the larger, Phobos, is only 14 miles across (22 kilometers), while the smaller, Deimos, is only 8 miles (13 km), making them some of the smallest moons in the solar system.

Both are also made up of material that resembles Type I or II carbonaceous chondrites, the substance that makes up asteroids. With their elongated shapes, they even look more like asteroids than moons.

Even from Mars, the moons don't look like moons. The more distant moon, Deimos, appears more like a star in the night sky. When it is full and shining at its brightest, it resembles Venus as seen on Earth. Phobos has the closest orbit to its primary of any moon in the solar system, but still only appears a third as wide as Earth's full moon.

Phobos orbits only 3,700 miles (6,000 km) from the Martian ground. Its surface is marred by debris that may have come from impacts on Mars. It travels around the planet three times a day, zipping across the Martian sky approximately once every four hours. The fast-flying moon appears to travel from west to east.

Deimos orbits much farther away, tending to stay 12,470 miles (20,069 km) from the red planet's surface. The moon takes about 30 hours, a little over a Martian day, to travel around its host.

Credit : Space.com

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Venus and the planet Mercury are the only two planets that don't have a single natural moon orbiting them. Figuring out why is one question keeping astronomers busy as they study the Solar System.

Astronomers have three explanations about how planets get a moon or moons. Perhaps the moon was "captured" as it drifted by the planet, which is what some scientists think happened to Phobos and Deimos (near Mars). Maybe an object smashed into the planet and the fragments eventually coalesced into a moon, which is the leading theory for how Earth's Moon came together. Or maybe moons arose from general accretion of matter as the solar system was formed, similar to how planets came together.

Considering the amount of stuff flying around the Solar System early in its history, it's quite surprising to some astronomers that Venus does not have a moon today. Perhaps, though, it had one in the distant past. In 2006, California Institute of Technology researchers Alex Alemi and David Stevenson presented at the American Astronomical Society's division of planetary sciences meeting and said Venus could have been smacked by a large rock at least twice.

Credit : Phys.org 

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