There are more than 200 moons in our solar system. Most major planets except Mercury and Venus have moons. Pluto and some other dwarf planets and many asteroids have small moons. Saturn and Jupiter have the largest number of moons, orbiting two dozen giant planets each. Only one moon orbits our planet.
The planets in our solar system come in two forms, some rocks and some gases. But all the moons in our solar system revolve around rocks and gas giants. Why are some moons in the solar system not created by gas? Are there gas moons anywhere in the universe?
All the moons in our solar system are rocks (Shutterstock)
Good reasons
Jonathan Lunin, head of the Department of Astronomy at Cornell University, told the website:Direct science(Live Science) There are some good reasons for the absence of gas moons nearby.
But even if we did not find any gaseous moons outside our solar system, under the right circumstances it would be possible. In particular, it depends on the mass of the Moon, the effect of ambient temperature and wave forces, and the gravitational pull of a nearby object such as the host planet orbiting the Moon.
To illustrate how these conditions can affect the gas moon, imagine that our moon’s rock formation has been replaced by pure hydrogen. Hydrogen gas is much less dense than rock, so immediately, the Moon will grow to the size of Earth. That means the “gas moon” is likely to be about the size of its parent planet, so it would be more appropriate to call it a “binary planet”.
Gas binary planets may be possible, but they are very rare because planetary formation usually leads to two planets merging or separating from each other. Therefore, no gas satellite has been detected so far.
There are some good reasons for not having gas satellites nearby (Shutterstock)
Large size and temperature
In fact, the sheer size of Jupiter-like gas giants is one reason for their existence. Because if it is so small, the force of gravity will not be strong enough to hold those light elements together.
Like gaseous planets, a gas must be larger than its rock counterparts because if it were so small it would not have enough gravity to hold lighter gases such as hydrogen and helium.
But size is not the only factor, temperature is also. “Let’s just take the moon as a rock,” says Lunin. “Then we’ve put the atmosphere of hydrogen around it. We know that the hydrogen atmosphere will leave very quickly due to the effects of heat.” Hydrogen evaporates due to the heat of the sun.
What this tells us is that if our moon were made entirely of hydrogen, it would not be stable. But even if our imaginary gas moon were the size of Earth and the temperature around it was too cold, the host planet would tear it up.
Earth’s Moon is subject to tidal forces from Earth, but is not disconnected (Shutterstock)
“Earth’s moon is subject to tidal forces from Earth, but it does not decompose because it is combined with some physical force,” says Lunin. “But the hypothetical gas is not like that on the moon because it is made of gas.
How is the gas moon possible?
The moon’s host planet must be very far and cold for a gas moon to be possible.
And if a gas moon were the same size as ours and located somewhere in our solar system, it would not run stable. But if the gas moon were approximately the size of Neptune and orbited Jupiter, the gravitational forces holding these massive objects together would prevent wave forces from destroying the Neptune-sized moon. It can be very stable.
A study published today (Wednesday) reports that the mass of the Milky Way galaxy is four to five times less than previously thought, results that overturn what is known to date about the galaxy that contains the planet Earth.
As astronomer François Hamer, co-author of the study published by the journal “Astronomy and Astrophysics,” explained to Agence France-Presse, the result is “the result of the Gaia revolution.” Gaia, a satellite dedicated to mapping the Milky Way galaxy, revealed the positions and motions of 1.8 billion stars in its latest data in 2022.
It represents a small fraction of the total contents of our spiral galaxy, a disk about 100,000 light-years in diameter and consisting of four large arms, one of which includes our Solar System, all of which extend around a very luminous core. .
The authors of the study report that by studying the Gaia data they were able to calculate the rotation curve of the Milky Way with unprecedented precision. The task is to determine the speed at which celestial bodies rotate around the center of the galaxy.
Observations of spiral galaxies have previously concluded that this curve is “flattening”, meaning that once a certain distance from the center is reached, the rate of rotation is constant.
But “this is the first time we find that the curve descends outside its disk,” according to Francois Hamer, “as if there wasn’t a lot of matter” in the galaxy between 50 and 80 thousand years from the center.
As a result, “the mass of our Milky Way Galaxy has been revised to very low values,” about 200 billion times the mass of the Sun, five times less than previous estimates.
The Milky Way Galaxy appears in the sky over the island of Gozo, Malta (Reuters)
“Bold Decisions”
The study, conducted by an international team and led by astronomers from the Paris Observatory and the National Center for Scientific Research in France, has a second major conclusion, as it questions “the relationship between luminous matter and dark matter.” Astronomer.
This hypothesis is also called thematic theme because it is so far invisible and undetectable. It is thought to provide the mass necessary for the coalescence of galaxies, and represents about six times the mass of luminous matter that contains stars and gas clouds. For the Milky Way, the study calculates that this ratio is much lower, with three times as much dark matter as bright matter.
But astronomer François Combes, a colleague of François Hammer at the Paris Observatory, told Agence France-Presse that the results were “a bit bold” or “perhaps not well founded.”
This is significant because this study focuses on low galactic radii, while astronomers typically calculate galactic masses by taking greater distances into account.
However, apart from gas, globular clusters, dwarf galaxies or the Magellanic Cloud, “up to this distance we have a lot of dark matter,” notes Francois Combe, a senior expert on galaxy evolution.
But the Gombe galaxy, about 80,000 light-years away from the center of the galaxy, welcomes “very precise work that will improve our knowledge of the stars and their rotation”.
François Hammer’s team defends this work by talking about the uniqueness of our galaxy. Unlike most spiral galaxies, which saw violent collisions between galaxies six billion years ago, the Milky Way “evolved very quietly for nine billion years,” Hamer says.
Also, the difference between the Milky Way and other spiral galaxies can be justified by the observational method, which relies on stars in the former and gas clouds in the latter.
Meanwhile, Françoise Combe believes the Milky Way galaxy is “not exceptional,” but in terms of dark matter, “it’s like the others.”
After 3 years of suffering from the corona virus and its variants, the severity of the virus decreased and the virus began to recover from the effects of the terrible epidemic, scientists began to warn about the “nipa” virus, which is transmitted by bats. , pigs and animals.
Although it has not started spreading, some virologists in Russia have warned about the danger of the “Nipah” virus, which has already started spreading in India, and it is said to be likely to cause a new epidemic in the world.
Russian scientists have said that if the Nipah virus undergoes genetic changes it could become a pandemic.
A Russian scientist said Nipah virus is a viral disease originating from bats and is currently spreading in India, Bangladesh and some countries in Southeast Asia.
We advise virologists not to travel to countries where infections with this virus have been reported, as the virus is not widespread and infections are few and far between in India and Southeast Asia.
Virologists advised to wash fruits and vegetables thoroughly, wash hands and wear masks, because there is currently no vaccine against this virus, and there are no drugs against it.
The disease is spread from animals to humans, from an infected person to others, through contaminated food and respiratory droplets.
The disease may show no symptoms, or may be accompanied by mild or severe respiratory infection or encephalitis, in the latter case it can lead to coma and death.
According to the Wall Street Journal, the outbreak has so far occurred in the city of Kozhikode in the Indian state of Kerala.
According to the Associated Press, many Americans joke about how bad they are at math, and their already poor scores on standardized math tests continue to decline.
Employers say America needs math geniuses like animated movies need superheroes. They believe America’s poor performance in math is no laughing matter, but a threat to national security and global economic competitiveness.
Jim Stigler, a professor of psychology at the University of California who studies the teaching and learning process in subjects including mathematics, believes that the technological advances that will lead the world in the next fifty years will come from other countries. Capital that America does not have.
The U.S. Department of Defense has called for a major effort to support education in science, technology, education and math, or “STEM” for short. The number of graduates in these categories in China is eight times that of their counterparts in the United States, and the number of engineers in Russia is four times that of those in the United States, he said.
For his part, Aspen Research Institute Vice President Josh Weiner says the matter is not just an academic issue. Last July, he warned that other countries, particularly China, were challenging America’s technological dominance. He explained that mathematics is needed to solve the fundamental challenges faced in the present era.
On the other hand, the number of jobs in mathematical occupations, i.e. jobs that use the dream of arithmetic and use advanced methods to perform calculations, analyze data, and solve problems, will increase by more than 30,000 per year. In the current decade, that’s the fastest rate compared to any other type of job, according to the U.S. Bureau of Labor Statistics.
