What are Some Prominent Features of Neptune?

Neptune is a distant planet among the eight planets of the solar system. According to the distance between the planets and the sun, Neptune is the eighth planet, the fourth largest planet in diameter, and the third largest planet in mass. Neptune's brightness is only 7.85, which can only be seen in astronomical telescopes. Because of its faint light blue light, Westerners call it Neptune in Roman mythology. In Chinese, it is translated as Neptune.

[hi wáng xng]

There were some difficulties when Neptune was discovered in 1848. At first people made some mistakes (Neptune was once mistaken for Uranus and disappeared for a while), Galileo observed the planet in 1612 and judged it as a satellite of Jupiter ^[2]

Neptune Ground Observation

Neptune cannot be seen by the naked eye, and its brightness is between the apparent magnitude +7.7 and +8.0, which is better than Jupiter's Galileo satellite, dwarf planets, Ceres and asteroids, Vesta, Pluto, Rainbow, Marriage and Shao The stars are dark. In an astronomical telescope or high-quality binoculars, Neptune appears as a small blue disk that looks similar to Uranus. Blue comes from methane in its atmosphere. Its small size makes research difficult; most of the data obtained from the telescope is quite limited, and it did not change until the Hubble Space Telescope and large ground-based telescope and adaptive optics technology appeared.

Neptune in the infrared (2 photos)

Neptune can be seen through binoculars, but if you want to see everything on the planet instead of just a small disc, then you need a large astronomical telescope. Mike Harvey's planet search chart indicates the position of Neptune in the sky (and the position of other planets) at this time, and then the Starry Night program is used to make more detailed customization.

2 Neptune Voyager 2

On August 25, 1989, the Voyager 2 probe launched by NASA flew over Neptune. This is the first time that humans have used a space probe to detect Neptune. It met Neptune at the closest point of 4,827 kilometers from Neptune, so that for the first time, humans could clearly see the face of Neptune, which is 4.5 billion kilometers away from Earth. It discovered six new satellites of Neptune, bringing its total number of satellites to eight; it first discovered that Neptune has five rings, three of them dim and two bright.

From more than 6000 photos of Neptune taken by Voyager 2, it was found that there are two huge black wind and cloud bands around 4345 kilometers wide and a storm area as large as the earth around the south pole of Neptune. They form a Jupiter-like red spot Big dark spots. This large black spot rotates counterclockwise along the center axis, and it takes 10 days for each 360 ° turn. Neptune also has magnetic fields and radiation bands, and most areas have aurorae like Earth's north and south poles. Neptune's atmosphere is turbulent. The atmosphere contains white clouds of frozen methane and a large area of cyclones. Following the cyclones is a hurricane with a speed of 640 kilometers per hour. There is a layer of smoke over Neptune caused by sunlight shining on methane in the atmosphere.

The average distance between Neptune and the sun is 4.496 billion kilometers, which is 30 times the distance from the earth to the sun. Neptune receives only 19% of the Earth's light and heat, so its surface is covered with a layer of ice that stretches thousands of kilometers thick, and the surface is surrounded by a dense atmosphere. Neptune has a diameter of 49,500 kilometers, which is 57 times the size of the earth. 57 The earth is so large, its mass is only 17 times that of the earth, so its density is also quite small. It takes 164.8 years for Neptune to revolve around the sun at a speed of 5.43 kilometers per second, and it takes 15 hours, 57 minutes, and 59 seconds to complete a revolution.

The magnetic field of Neptune is the same as that of Uranus, and its position is very strange, which is probably caused by the movement of conductive material (probably water) in the planet's crust.

Neptune future exploration

NASA is studying a possible Neptune exploration mission.

NASA proposed the concept of launching the Neptune orbiter in 2005. It plans to send one or two probes to Triton in 2016 and detect the atmosphere of Neptune, similar to the Galileo probe.

The flagship or cornerstone mission is another possible Neptune exploration mission that requires more than $ 1 billion in funding. Funding for these missions is shared by NASA and the European Space Agency. This future plan may become Europa or Titan, and is not expected to launch before 2040.

Astronomers are interested in detecting Neptune's system, some scholars believe that NASA-sponsored Xinjiang missions (such as New Horizons and Juno) can provide $ 1 billion in funding, and that the probe could be launched in 2010. This probe can not only study Neptune and its systems, but also pass Jupiter and Saturn, save fuel by its gravity, and then approach two or three celestial bodies in the Kuiper belt. New Horizons will also detect other targets after passing Pluto.

Neptune's Great Dark Spot

Merge Atlas (2 photos)

In 1989, NASA's Voyager 2 spacecraft discovered The Great Dark Spot. At 22 degrees south latitude on the surface of Neptune, some egg-shaped vortexes similar to Jupiter's Great Red Spot and Saturn's Great White Spot rotate in a counterclockwise direction with a period of about 16 days, called "big black spots". Because the Great Dark Spot orbits Neptune every 18.3 hours, which is longer than the rotation period of Neptune, the latitude near the Great Dark Spot blows a strong westerly wind with a speed of 300 meters per second. Voyager 2 also found a small dark spot on the southern hemisphere, an irregular small cluster of white smoke flying around the planet at a rate of about 16 hours, known as "The Scooter". It may be a plume rising from the lower part of the atmosphere, but its true nature is still a mystery.

However, on November 2, 1994, Hubble's observation of Neptune showed that the large dark spots disappeared! It may just dissipate like this, or it may be temporarily obscured by other parts of the atmosphere. A few months later, the Hubble Telescope discovered a new dark spot in Neptune's northern hemisphere. This indicates that Neptune's atmosphere changes frequently, which may be caused by subtle changes in the temperature difference between the top and bottom of the cloud.

Neptune Storm

The storm on Neptune is the strongest of Jupiter-like planets in the solar system. Considering that it is located on the periphery of the solar system and receives 1,000 times less sunlight than Earth (still very bright, depending on the magnitude of -21), this phenomenon does not meet the original expectations of scientists. It used to be believed that the farther the planet was from the sun, the less energy needed to drive the storm. The wind speed on Jupiter has reached hundreds of kilometers per hour, and on the more distant Neptune, scientists have found that the wind speed is not slower but faster (1600 km / h). One possible reason for this apparent anomaly is that if the storm has enough energy, it will generate turbulence, which will slow down the wind speed (as on Jupiter). However, on Neptune, solar energy is too weak, and once it begins to wind, they encounter few obstacles, and can maintain extremely high speeds. Neptune releases more energy than it gets from the sun, so these storms may also have an undetermined intrinsic source of energy.

Merge Atlas (2 photos)

In 2007, it was found that Neptune's South Pole was about 10 ° C higher than its average surface temperature (about -200 ° C). This 10 ° C higher temperature is enough to release methane into space, while methane is frozen in the upper atmosphere of Neptune in other regions. This relative hot spot was formed because Neptune's orbital inclination caused its South Pole to be exposed to sunlight over the past 40 years, and one Neptune year is equivalent to 165 Earth years. As Neptune moves closer to the sun, its south pole will gradually darken, and the north pole will be illuminated by the sun, which will cause the methane release area to shift from the south pole to the north pole.