Neptune, the outermost of the eight planets in the Solar System, is an ice giant with an average temperature of only minus 218 °C, because it is far enough from the sun, nearly 4.5 billion kilometers, and its own mass is not large enough, about 17 times that of Earth, and the heat inside is not enough to warm the surface, and the latest observations show that Neptune has become colder in recent years.
A paper published April 11 in the Journal of Planetary Science said that Neptune's overall temperature dropped "unexpectedly", especially in the equatorial zone, but its south pole is heating up sharply, which is considered a very abnormal situation.
On our earth, due to the reason of the earth's rotation state, sunlight will shine directly into the earth's equator and the tropical areas on both sides every year, so the earth's equator and its sides have the highest temperature, the earth's poles get the least amount of sunlight energy a year, so the two poles are the coldest, in fact, Neptune's rotation state is basically the same as the earth, then it should also be the hottest in the equatorial region and the coldest in both places, and because Neptune's axis of rotation and the sun's ecliptic plane also have an inclination, and the angle is similar to that of the earth, So neptune's surface also has seasonal temperature changes like Earth's, and its seasons change according to its solar orbit, while Neptune takes 165 years to orbit the sun, and a season lasts about 41 years.
The picture above shows the direction and inclination of the rotation axis of the eight planets of the Solar System
Summer temperatures in the northern and southern hemispheres of the Earth will be very high, and Neptune should be the same, but curiously, the researchers observed the early summer season of Neptune's southern hemisphere, but found that the equatorial zone has become colder, and the normal situation should be that the surface temperature of the southern hemisphere is gradually rising.
Michael Roman, the lead author of the paper and a postdoctoral research assistant at the University of Leicester in the United Kingdom, said: "Since 2005 we have been observing in the early summer of Neptune's southern hemisphere, and we thought that the temperature there would slowly rise instead of falling, but the actual situation is just the opposite. ”
The researchers also took nearly 100 thermal infrared images of Neptune taken in 17 years, you can clearly see that the temperature of Neptune is gradually decreasing, in the 15 years from 2003 to 2018, the average temperature of Neptune plummeted by 8 ° C, especially in the equatorial zone and the southern hemisphere near the equator, from the following figure can be clearly seen that the temperature has dropped a lot, but the Antarctic region is the opposite, the temperature is much higher than before, which shows that Neptune is becoming strange.
The data shows that in the two years from 2018 to 2020, the temperature in Neptune's Antarctic region rose sharply by 11°C, which is very unusual and has never been seen before. Another author, Glenn Orton of the California Institute of Technology, added: "It's so unexpected that we're less than halfway through a season on Neptune, and the changes are so huge and rapid." ”
If the earth's temperature had changed as much as neptune's, there would have been no doubt a devastating catastrophe, since the earth's global warming situation, Today, the average temperature of the earth is actually only about 1.3 ° C higher than before the industrial revolution, the current human efforts aim to control the average temperature of the earth by 2050 to a level of 1.5 ° C higher than before the industrial revolution, if the average temperature of the earth increases by 8 ° C, then almost all the glaciers on the earth will melt, the sea level will rise by more than 60 meters, most of the plains on the earth will be flooded, and these places are inhabited by 90% of human beings. At the same time, the entire tropical and nearby areas of the Earth on both sides will become uninhabitable to humans.
So what exactly caused Neptune to have such a drastic temperature anomaly? Many friends may think that it is the influence of sunlight on the surface of Neptune, but in fact, this is not the reason why the sunlight illuminates the surface of Neptune, because Neptune is too far away from the sun, and the energy it can receive from the sunlight is actually very small.
At present, astronomers do not know the reason, speculating that the abnormal change in the temperature of Neptune may be due to changes in the chemical composition of Neptune's stratosphere, or a random weather pattern, or it may be the reason for the reduction of neptune's internal activity, which makes it less heat radiating outward from the inside, so there is a great cooling on the surface, but its Antarctic region is an exception, it may be that Neptune's internal activity radiates outward from here. But to really unravel this problem, continuous observation and research are needed, and in the future, the James Webb Space Telescope will also open the observation of Neptune, and the clear photos it takes will help to study these media on Neptune.
Resources:
"Reference News Network" April 14 article "Neptune climate changes drastically"
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