In June 2019, an automated survey of ATLAS (Asteroid Ground Impact Final Warning System) discovered a new object moving on a background star. Originally called 2019 LD2, it is considered to be an asteroid orbiting the sun near Jupiter. However, an amateur astronomer noticed that it looked blurry, rather than punctate, which meant it was more like a comet: the cold surface of matter turned into gas when heated by the sun.
After checking the archived image, astronomers determined that it had been “active” for at least a few months. Then change the name of the object to P/2019 LD2, indicating its status as a periodic comet.
Images from other observatories also confirm this, including Hubble. When they observed the comet in April 2020, they found that its tail was quite large, extending about 600,000 kilometers, almost twice the distance between the moon and the earth! Note that the nucleus (the solid part of the comet) may only be about 4 kilometers away.
Calculations show that during that time period, it lost approximately 80 kg of water ice per second. It is also emitting gases such as carbon monoxide (approximately 50 kg/sec), carbon dioxide (7 kg/sec) and diatomic carbon (two carbon atoms combined; the rate is 40 grams per second).
It may sound like a lot, but it turns out just Start deflating like this… and it won̵
When this happens, it will become an interstellar comet like 2I/Borisov or’Oumuamua, both of which have recently passed through our solar system (I will note that they are not alien spacecraft).
This is appropriate, because it may have also begun life in the outer solar system.
P/2019 LD2 is very likely to be Neptune Celestial Body, This is an ice body, orbiting Neptune orbiting the sun in the Kuiper belt. Over time, Neptune’s very slight push caused by gravity pushes it into a smaller orbit closer to the sun. Eventually, its distance is close enough that Neptune can yank it harder, causing a major change in its orbit, placing it in an orbit between Jupiter and Neptune (about 800 million to 3 billion kilometers from the sun).Objects in orbit like this are called Centaur.
Centaur is very interesting. Over time, gas giants often change their trajectories. Usually, after millions of years in this part of the solar system, they are too close to one of the planets. They either fall into the inner solar system (and become what we call Jupiter family comets), or they are thrown out of the solar system completely.Therefore, we call them transition objects*.
P / 2019 What is the fate of LD2? Where did it come from?
Observations of an object over time can be used to determine its orbit, which can then be projected into the past and the future. The problem is that we cannot accurately measure the orbit. There will always be some uncertainty. The more vaguely you predict its future location (or its past location), the more vague it is and the more space it may occupy. This makes this prognosis easier.
To solve this problem, astronomers did something clever: They simulated its orbit using the so-called Monte Carlo technique. They adopted the physical characteristics of the orbit (shape, distance from the sun, inclination, etc.), and then made very small changes to each orbit to form a slightly different orbit. Then, they apply it to the past and the future, and observe its effects. They create virtual object queues time and time again, and the path of each object is slightly different. In this way, you can understand the history and future of the object more statistically.
Their discovery of P/2019 LD2 is that it only entered Jupiter’s space about 2.5 years ago! Prior to this, it was a standard-release Centaur, but it has only recently been pushed into its current orbit.
And its future?They found that it is likely that it will only stay on its current orbit 8 or 9 years later. After that, it is likely to fall into the inner solar system and become a comet in the Jupiter family. This means it is only pitting near Jupiter.
Even if it is temporary. In 340,000 years, 50% of it was ejected from the solar system, and in 4 million years, this proportion rose to 95%.
With the use of the solar system, it is likely that billions of these objects have been thrown out. And there are billions of stars, such as the sun… which is why astronomers believe that the Milky Way is full of rogue interstellar ice balls (such as P/2019 LD2), and why it is not surprising to see them also pass through our solar system.
In the distant future, will some alien scientists see LD2 pass through their own system? What will they do? Knowing that all parts of our neighborhood will be scattered in stars, it’s interesting and surprising, from citizens of our solar system to citizens of the Milky Way.
*Given that they are named after the mythical half-human/half-horse creatures, which is great, the solution is this.