Die on Mars

"Comet?" Tang Yue was stunned.

Maidong was installing line C1002. Hearing what the old cat said, he raised his head and asked, "Is it the comet from Halley's Comet?"

"Yes, it is a broom star." Old Cat replied, "But it is not Halley's Comet. This is a new comet. There is no record of it in history. It is a non-periodic comet. Its orbit is not an ellipse but a double one. curve."

"When did you find out?" Tang Yue was a little surprised.

"Just now, I just confirmed its existence." Old Mao called up the observation data on a monitor, "Because this star has brightened seven times in the past forty-eight hours, and its visual magnitude has suddenly increased from sixth magnitude. When it reached fourth magnitude, I originally thought it was a variable star, but then I discovered that it was an object in the solar system, and its brightness increased rapidly because it was approaching the sun at high speed."

"So we can see the comet?" Maidong was surprised.

"What does this mean?" Tang Yue's reaction was very nervous. He immediately thought of the drama of an asteroid hitting the earth, "Isn't there any danger?"

"The situation is unclear at the moment. I have turned on the survey telescope on the space station and am preparing to track it. I will soon be able to predict its orbit." Lao Mao replied, "Judging from the current results, this is a planet that has never come before." The source of comets passing through the solar system may be the Oort cloud..."

"It doesn't matter where it comes from, as long as it doesn't come to Mars." Tang Yue muttered.

"Can I see it?" Maidong asked.

"Yes, Miss Maidong." The old cat said, "But its current brightness is not higher than most stars in the night sky. However, as time goes by, the distance from the sun gets closer and closer, and the visual magnitude of the comet It will continue to improve.”

Maidong straightened up and looked around. All the stars in the sky were shining brightly, but she couldn't find the broom-like comet she imagined.

"But I can't find it. Isn't the comet a big broom?"

"It's not close enough to the sun, so the tail is not obvious yet, but it won't be long before you can find it. This is a rare large comet, and its tail should be more than 280,000 kilometers in diameter. ." The old cat said, "Do you know what this size is?"

Maidong shook his head.

"The diameter of Jupiter is only 140,000 kilometers, and its diameter is twice that of Jupiter." Lao Mao explained, "When Comet Tomcat-Tang-Mai 1 is closest to the sun, it will become the brightest in the sky. That star will also drag a huge tail hundreds of millions of kilometers long, sweeping across the entire night sky."

"Wait, wait, what did you just say? What is Tomcat-Tang-Mai?" Tang Yue frowned. The old cat often did not speak human words.

"The name of the comet." The old cat answered.

"You said before that this was a new comet with no records."

"Yes, so the name was just given by me." Old Cat nodded, "According to the regulations of the International Astronomical Union, comets are named by the discoverer."

Tang Yue held the name in his mouth and chewed it several times before realizing that the old cat was named after the three of them.

Comet Laomao-Don-Mai 1.

This is probably the last comet discovered and named in human history.

"How long will it take before you can confirm its orbit?" Tang Yue asked.

"The space station's telescope is tracking, and the prediction results will be available in a few days. What can be confirmed at present is that this comet will definitely enter the proto-Earth orbit, which means that it will pass through the orbit of Mars, but we don't know whether it will collide with Mars. It passed by." The old cat replied, "But you don't have to worry about anything going wrong. Although a comet is a celestial body that looks huge and scary, 99% of its components are thin gases and are truly solid. The wisdom core is only a few tens of kilometers in diameter."

"Does that mean it can't hit Mars?" Tang Yue asked.

"It's impossible. The comet's flight speed is too high, far exceeding the breakaway speed of all planets in the solar system. Unless the Tomcat-Tang-Mai comet plunges into the Roche limit of the two and is directly torn apart by tidal forces, Mars will not be able to Capture it." The old cat shook his head.

"We can do a simple calculation. The main component of the core is water, so its density is similar to ice. The average density of Mars is very low, about four grams per cubic centimeter. According to the calculation formula of the fluid Roche limit, d=2.44 R√(ρM/ρm), the result can be found to be 7004 kilometers.”

"That is to say, this comet must be at least close to the surface of Mars to within 3,600 kilometers before it can be torn into pieces and then hit the surface of Mars... I tell you this news not to make you fearful, but to make you fearful. Pay attention to watching when the time comes." Old Cat continued, "This comet may become the brightest celestial object in this century, and it is a rare astronomical spectacle."

Tang Yue breathed a sigh of relief.

He would rather not see the astronomical wonders of Laoshizi than to have any complications.

The old cat suddenly told him that at this time, a celestial body was heading straight towards the orbit of Mars at a high speed of seventy or eighty kilometers per second. This kind of news would be frightening to anyone.

In Maidong's eyes, this is very romantic.

But in Tang Yue's opinion, this was simply a nuclear strike warning.

"As long as something like Shoemaker Levi 9 doesn't happen, old cat, you have to know that human beings are naturally afraid of this kind of celestial body. After all, our ancestors are creatures that survived this kind of space nuclear attack. , If it hadn't been for the asteroid that fell into the Gulf of Mexico 65 million years ago, I might have a lizard face now." Tang Yue said, "I don't care about spectacles or anything like the disappearance of the earth. I have seen all the wonders, what else can surprise me?”

"It was Jupiter that tore Shoemaker apart." said the old cat. "Compared with Jupiter, Mars is far behind."

"Why did a comet suddenly come at this time?" Maidong asked as he tightened the screws.

"It doesn't come suddenly, it's just that we just discovered it." The old cat replied, "When it crossed the orbit of Neptune and Uranus, it was too far away and almost emitted no light, so we couldn't observe it. In fact, it had already entered the solar system. .”

"Will it come again in the future?"

"No." The old cat said, "This is a wandering comet. Once it leaves, it will never come back. In fact, most comets are like this, drifting around, being pulled by the gravity of the sun, and turning around in a circle. Gone again, never to come back again.”

"Wandering... wandering." Maidong said softly, tightening the last screw and completing the installation of line C1002. "Where did you come from? Where is the way back?"

She looked around again, trying to find the wandering celestial body that broke into the solar system.

But as Lao Mao said, the brightness of the comet was still too low at this time, and it was hidden in the boundless sea of ​​stars like a drop of water.

This is an ancient starry sky.

The youngest light that fell into the girl's eyes came from four years ago.