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Neptune – Worldatlas.com

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Orbiting the sun at a distance of 2.8 billion miles (4.5 billion kilometers), Neptune is the fourth-largest planet by diameter and third-largest by mass, having a diameter of 30,598 miles (49,244 kilometers). Strangely, it is slightly more massive than Uranus, which is strange given that the mass of the gas giants should increase the closer you get to the sun. This has led astronomers to predict that Neptune may have formed much closer to the sun than Uranus did. Still, gravitational perturbations from the other gas giants caused its orbit to migrate outwards. In the 174 years since astronomers found Neptune, it has only been visited by a spacecraft on a single occasion, when Voyager 2 passed by the giant planet in 1989. Voyager 2 revealed a truly remarkable and complex world. Neptune is a warmer planet despite it being further from the sun than Uranus. The core of Neptune is predicted to reach temperatures of (7,000 degrees Celsius), while its upper layers reach temperatures as low as minus 328 degrees Fahrenheit (minus 200 degrees Celsius). This gigantic difference in temperature between Neptune’s outer and inner layers is believed to cause Neptune’s dynamic weather system. Voyager 2 measured the fastest known winds in the solar system, reaching speeds of 1,500 miles per hour (2,400 km/h).

Although classified as gas giants, both Uranus and Neptune have enough unique characteristics that they belong to their own classification: ice giants. Unlike Jupiter and Saturn, Uranus and Neptune contain a much higher abundance of ices, such as water, ammonia, and methane. Like Jupiter and Saturn, Neptune is composed mainly of hydrogen and helium. However, hydrogen and helium only make up a fraction of Neptune’s density. Various ices determine the density of Neptune, making it both a gas giant and an ice giant

Observational History 

An Image of Neptune Taken by Voyager 2, NASA

Neptune was the latest planet to be discovered in our solar system and, interestingly, the only one to be found using mathematics rather than a telescope. The discovery of Neptune was tied directly to the discovery of Uranus. In 1781, the astronomer William Herschel discovered the planet Uranus. After the discovery of Uranus, astronomers were puzzled over its orbit. The orbit of Uranus was tilted so that the mass of Uranus and the gravitational pull of the sun could not explain. In 1821, Alexis Bouvard predicted that the orbit of Uranus could be explained if another planet was orbiting the sun outside of Uranus’s orbit. He was able to predict the orbit of this eighth planet, and in 1846, astronomers pointed their telescopes to the sky and found Neptune, just as the math had predicted. Given Neptune’s distance from us, it is not an easy world to study. For over a hundred years, virtually nothing was known about Neptune. Astronomers would not get their first up-close view of Neptune until 1989 when the Voyager 2 spacecraft completed the first-ever flyby of Neptune. To date, the Voyager 2 flyby has been the only mission to Neptune, and it raised far more questions than it answered. Neptune is one of the most mysterious worlds in the solar system, and our knowledge of it is definitely lacking. However, as telescopes have become more powerful, astronomers have observed Neptune in more detail than in the past. Still, most of what is known about Neptune comes from the Voyager 2 flyby. 

Orbit And Rotation

solar system
The Planets in Our Solar System and their Orbits

The average distance between Neptune and the sun is 2.8 billion miles (4.5 billion kilometers). It takes Neptune nearly 170 Earth years to complete one orbit around the sun at such a vast distance. Since its discovery, Neptune has only completed one full sun rotation. Like all the other planets, Neptune orbits the sun in an ellipse, meaning that the distance between the sun and Neptune changes through the planet’s orbit. Neptune is roughly 2.76 billion miles (4.45 billion kilometers) away from the sun during its closest approach. Neptune is 2.81 billion miles (4.53 billion kilometers) away from the sun during its furthest approach. 

Neptune’s orbit and location in the solar system have a profound impact on the solar system’s outer regions. Just beyond the orbit of Neptune is the Kuiper Belt, a vast collection of comets and other forms of planetary debris. Short-period comets primarily come from the Kuiper Belt, and it is the gravitational pull of Neptune that generally pulls them on a trajectory towards the inner solar system. 

As a gas giant, Neptune has an interesting rotation. The axis tilt of Neptune is only 28 degrees, which is quite similar to Earth’s 23 degrees. As a result, Neptune experiences seasonal changes similar to Earth’s, the significant difference being their length. Since it takes Neptune 170 years to orbit the sun, its seasons generally last up to 40 Earth years. Since Neptune is primarily composed of gas, Neptune’s atmosphere rotates at a different rate than the planet itself. The actual rotation of a gas giant is generally determined by the rotation of the planet’s magnetic field. Neptune takes roughly 16 hours for the planet to rotate once about its axis. Along Neptune’s equator, it takes the atmosphere 18 years to rotate around the planet. In the polar regions, it takes 12 hours. This difference in rotation is one factor contributing to Neptune’s high wind speeds. 

Neptune’s Atmosphere 

neptune atmosphere
The Blue-Green Atmosphere of Neptune as Captured by Voyager 2, NASA

The atmosphere of Neptune is similar to that of Uranus and the other gas giants. Neptune’s atmosphere is about 80% hydrogen and 19% helium in its upper layers. The remaining 1% is composed of various ices, the most notable of which is methane. On Uranus, methane in the upper atmosphere absorbs incoming red light and scatters blue light, causing Uranus to be cyan-green. Neptune contains a similar amount of methane as Uranus, which is one reason why Neptune is blue. However, based on what is currently known, Neptune should be the same color as Uranus, yet Neptune is a much deeper blue than its planetary neighbor. As of yet, scientists do not know all the factors that contribute to Neptune’s color. 

The atmosphere of Neptune can be divided into two central regions: the troposphere and the stratosphere. The troposphere composes the lower regions of Neptune’s atmosphere, while the stratosphere composes the upper areas. In the troposphere, temperatures increase with altitude. In the stratosphere, the opposite occurs, and temperatures decrease with altitude. Temperatures between the troposphere and stratosphere vary wildly. In the troposphere, temperatures average around 32 degrees Fahrenheit (Zero degrees Celsius), while temperatures in the upper stratosphere drop as low as minus 328 degrees Fahrenheit (minus 200 degrees Celsius). The troposphere is characterized by an abundance of clouds that can form at higher temperatures. Clouds in the troposphere are primarily made of methane, ammonia, and hydrogen sulfide. The troposphere is also where most of Neptune’s weather occurs.

Neptune is home to the fastest recorded winds in the solar system. Voyager 2 recorded wind speeds of over 1,500 miles per hour (2,400 km/h), which happens to be faster than the speed of sound on Earth. If Neptune’s winds were to occur in Earth’s atmosphere, they would be supersonic winds. Interestingly, since air is the medium that sound travels through, the sound speed depends on the density of air. Air density on Neptune is far higher than on Earth, so winds do not exceed the speed of sound on Neptune. 

Internal Structure Of Neptune

neptune
The True Colors of Neptunes Surface and Cloud, Captured by Voyager 2, NASA

Neptune’s atmosphere composes an estimated 10% to 20% of the distance to Neptune’s core and only about 5% of the planet’s total mass. Below the atmosphere is a world, unlike anything we are familiar with on Earth. At the very bottom of Neptune’s atmosphere, pressures are 100,000 times larger than on Earth. Below the atmosphere is the mantle. On Earth, the mantle is composed mostly of molten rock. On Neptune, the mantle is comprised of various ices such as methane, water, and ammonia. At a depth of around 4,350 miles (7,000 kilometers), pressures and temperatures in the mantle become so extreme that the carbon atoms in methane molecules break apart and form into diamond, which then proceeds to fall through the mantle as a kind of diamond rain. There may even be an ocean of liquid carbon in the lower mantle, where giant diamond bergs float freely. 

Below the mantle is the core of Neptune. The core of Neptune is largely a mystery, and so scientists rely on models to predict what may be occurring there. It is assumed that the core of Neptune is rocky, composed mostly of metal and silicate rock. The core itself is likely larger than the Earth and has a mass of around 1.2 Earths. Temperatures are estimated to reach as high as 9,260 degrees Fahrenheit (5,126 degrees Celsius). 

Neptune’s Moons

neptune and triton
A Composite Image Showing both Neptune and Its Moon Triton, NASA

Neptune is orbited by 14 known moons. Of those 14 moons, only one, called Triton, is large enough to be spherical. Triton comprises roughly 99% of the total mass of Neptune’s entire moon system. Triton has a diameter of 1,680 miles (2,710 kilometers), making it the seventh-largest moon in the solar system. Triton was discovered only 17 days after the discovery of Neptune, yet not much was known about this moon until the Voyager 2 flyby of Neptune. Triton has become one of the strangest, most interesting moons in the solar system. Unlike every other moon, the orbit of Triton is retrograde, meaning it orbits in the opposite direction of Neptune’s rotation. This suggests that Triton never actually formed in orbit around Neptune. Instead, Triton was likely a dwarf planet that formed in the Kuiper Belt and just happened to get caught in Neptune’s gravity. Although the retrograde motion of Triton may not sound significant, it has actually doomed this moon. The orbit of Triton is slowly degrading, and Triton is currently spiraling towards Neptune. In about 3.6 billion years, Triton will be so close to Neptune that it will be ripped apart by Neptune’s gravity. 

When Voyager 2 approached Triton in 1989, it recorded the coldest measured temperature in the solar system. The surface of Triton drops to a frigid minus 391 degrees Fahrenheit (minus 235 degrees Celsius). Voyager 2 found clear evidence of geologic activity on Triton despite these cold temperatures. Voyager 2 found evidence of volcanism and tectonic activity and a lack of impact craters. Unfortunately, Voyager 2 was only able to map 40% of Triton’s surface, so Triton is one of the most mysterious worlds in the solar system. 

Neptune Fact Sheet

Diameter  30,598 miles (49,244 kilometres)

Mass

17 Earths

Moons

14

Rings

5

Distance from the sun

2.8 billion miles (4.5 billion kilometers)

Length of year

170 Earth years

Length of day

16 hours

Surface temperature 

minus 328 degrees Fahrenheit (minus 200 degrees Fahrenheit)

Atmospheric composition 

80% hydrogen, 19% helium, 1% methane

Surface composition 

Water, methane, ammonia, silicate rock

Discovery date 

September 23, 1846

Discovered by 

Urbain Le Verrier

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Astronaut study reveals effects of space travel on human bones – Euronews

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By Will Dunham

WASHINGTON – A study of bone loss in 17 astronauts who flew aboard the International Space Station is providing a fuller understanding of the effects of space travel on the human body and steps that can mitigate it, crucial knowledge ahead of potential ambitious future missions.

The research amassed new data on bone loss in astronauts caused by the microgravity conditions of space and the degree to which bone mineral density can be regained on Earth. It involved 14 male and three female astronauts, average age 47, whose missions ranged from four to seven months in space, with an average of about 5-1/2 months.

A year after returning to Earth, the astronauts on average exhibited 2.1% reduced bone mineral density at the tibia – one of the bones of the lower leg – and 1.3% reduced bone strength. Nine did not recover bone mineral density after the space flight, experiencing permanent loss.

“We know that astronauts lose bone on long-duration spaceflight. What’s novel about this study is that we followed astronauts for one year after their space travel to understand if and how bone recovers,” said University of Calgary professor Leigh Gabel, an exercise scientist who was the lead author of the research published this week in the journal Scientific Reports https://www.nature.com/articles/s41598-022-13461-1.

“Astronauts experienced significant bone loss during six-month spaceflights – loss that we would expect to see in older adults over two decades on Earth, and they only recovered about half of that loss after one year back on Earth,” Gabel said.

The bone loss occurs because bones that typically would be weight-bearing on Earth do not carry weight in space. Space agencies are going to need to improve countermeasures – exercise regimes and nutrition – to help prevent bone loss, Gabel said.

“During spaceflight, fine bone structures thin, and eventually some of the bone rods disconnect from one another. Once the astronaut comes back to Earth, the remaining bone connections can thicken and strengthen, but the ones that disconnected in space can’t be rebuilt, so the astronaut’s overall bone structure permanently changes,” Gabel said.

The study’s astronauts flew on the space station in the past seven years. The study did not give their nationalities but they were from the U.S. space agency NASA, Canadian Space Agency, European Space Agency and Japan Aerospace Exploration Agency.

Space travel poses various challenges to the human body – key concerns for space agencies as they plan new explorations. For instance, NASA is aiming to send astronauts back to the moon, a mission now planned for 2025 at the earliest. That could be a prelude to future astronaut missions to Mars or a longer-term presence on the lunar surface.

“Microgravity affects a lot of body systems, muscle and bone being among them,” Gabel said.

“The cardiovascular system also experiences many changes. Without gravity pulling blood towards our feet, astronauts experience a fluid shift that causes more blood to pool in the upper body. This can affect the cardiovascular system and vision.

“Radiation is also a large health concern for astronauts as the further they travel from Earth the greater exposure to the sun’s radiation and increased cancer risk,” Gabel said.

The study showed that longer space missions resulted both in more bone loss and a lower likelihood of recovering bone afterward. In-flight exercise – resistance training on the space station – proved important for preventing muscle and bone loss. Astronauts who performed more deadlifts compared to what they usually did on Earth were found to be more likely to recover bone after the mission.

“There is a lot we still do not know regarding how microgravity affects human health, particularly on space missions longer than six months, and on the long-term health consequences,” Gabel said. “We really hope that bone loss eventually plateaus on longer missions, that people will stop losing bone, but we don’t know.”

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Understanding Plants Is Key to Finding a Cure for Cancer – SciTechDaily

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The scientists state that if they can understand unchecked plant growth, they believe they can find a cure for cancer.

If scientists can fully understand plant growth, they might be able to find a cancer cure

In order to increase agricultural yields, it is important to understand how plants process light. Plants use light to determine when to grow and bloom. Plants find light using proteins called photoreceptors. However, understanding plants have impacts in fields other than agriculture.  Ullas Pedmale, an assistant professor at Cold Spring Harbor Laboratory (CSHL), and his colleagues have discovered how the proteins UBP12 and UBP13 regulate the activity of a CRY2 photoreceptor. Their finding could make new growth-control strategies apparent, with potential implications well beyond agriculture.

There are CRY photoreceptors in both plants and people. They are connected to a number of conditions including diabetes, cancer, and several brain disorders.  CRY2 helps in regulating growth in both people and plants. Uncontrolled development in plants reduces their viability, whereas it causes cancer in humans. “If we understand growth,” Pedmale says, “we can cure cancer.”

Plant CRY2 Protein

Manipulating the levels of CRY2 and UBP12 and UBP13 proteins in Arabidopsis thaliana plants affects growth. The first plant from the left shows normal growth. The second plant is missing CRY2 and grew too much. The third plant lacked UBP12 and UBP13 and grew shorter. The fourth plant had high levels of UBP12 and UBP13, and the fifth had high levels of CRY2. Credit: Pedmale lab/CSHL, 2022

Plants need the right amount of CRY2 to know when to grow and flower. Pedmale and former postdoctoral fellow Louise Lindbäck discovered that manipulating UBP12 and UBP13 can change the amount of CRY2 in plants. They found that increasing UBP12 and UBP13 reduces CRY2 levels. This made plants think there wasn’t enough light. In response, they grew longer, abnormal stems to reach more. Pedmale says:

“We have a way to understand growth here—and we could manipulate growth just by manipulating two proteins. We have found a way we can actually increase flower output. You need flowering for food. If there’s no flower, there is no grain, no rice, no wheat, no maize.”

Pedmale and Lindbäck didn’t know exactly how UBP12 and UBP13 regulated CRY2. When the researchers took a closer look, they made a surprising discovery. In humans and other organisms, versions of UBP12 and UBP13 protect CRY photoreceptors from degradation. But in plants, the team saw the opposite. UBP12 and UBP13 were actually helping degrade CRY2 instead. Lindbäck, who is currently a research and developmental engineer at Nordic Biomarker in Sweden, explains:

“From literature, it’s known that if you find an interaction like this, it will protect from degradation. Initially, we saw the opposite, and we thought, ‘okay, maybe I did something wrong,’ but then when I did it a few times, we realized, ‘okay, this is true.’ Instead of protecting CRY2, it causes CRY2 to degrade.”

Pedmale hopes their discovery will help plant researchers and plant breeders improve crop yields. He also hopes his work helps inform cancer research. “My colleagues at CSHL are working hard trying to understand cancer,” he says. “We are coming at it from a different angle with plants.”

The study was funded by the National Institutes of Health. 

Reference: “UBP12 and UBP13 deubiquitinases destabilize the CRY2 blue light receptor to regulate Arabidopsis growth” by Louise N. Lindbäck, Yuzhao Hu, Amanda Ackermann, Oliver Artz and Ullas V. Pedmale, 13 June 2022, Current Biology. 
DOI: 10.1016/j.cub.2022.05.046

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Rocket Lab's Lunar Photon Completes Sixth Orbit Raise for NASA's CAPSTONE Mission to The Moon – Parabolic Arc – Parabolic Arc

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CAPSTONE (Credit: Terran Orbital)

LONG BEACH, Calif. (Rocket Lab PR) — Rocket Lab USA, Inc. (Nasdaq: RKLB) (“Rocket Lab” or “the Company”), a leading launch and space systems company, today confirmed its Photon Lunar spacecraft successfully completed a sixth on-orbit burn of the HyperCurie engine, bringing the CAPSTONE satellite closer to the Moon. Lunar Photon’s apogee – the point at which the spacecraft is farthest from Earth during its orbit – is now 43,297 miles (69,680 km).

This sixth burn was originally scheduled to be two burns, but Rocket Lab’s space systems team determined the HyperCurie engine would be capable of performing a single maneuver to accomplish the same delta-v, so combined the two.

The next and final burn is designed to set CAPSTONE on a ballistic lunar transfer trajectory to the Moon travelling at 24,500 mph (39,400 km/h) to break free of Earth’s orbit. This final maneuver is currently scheduled to take place as early as July 4th. After separating from Lunar Photon, CAPSTONE will use its own propulsion and the Sun’s gravity to navigate the rest of the way to the Moon, a four-month journey that will have CAPSTONE arriving to its lunar orbit on Nov. 13.

ABOUT CAPSTONE:

Designed and built Terran Orbital, and owned and operated by Advanced Space on behalf of NASA, the Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment (CAPSTONE) satellite will be the first spacecraft to test the Near Rectilinear Halo Orbit (NRHO) around the Moon. This is the same orbit intended for NASA’s Gateway, a multipurpose Moon-orbiting station that will provide essential support for long-term astronaut lunar missions as part of the Artemis program. CAPSTONE was successfully launched to space on Rocket Lab’s Electron launch vehicle on June 28.

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