The mysterious bright spot on Ceres, is it really an ocean? Scientists: there may even be life

For a long time, scientists have focused on stars, planets, and moons in space exploration, with little regard for small objects such as asteroids and dwarf planets, the main reason being that small objects are directly excluded from the list of habitable planets because they are too small in size and mass. But in recent years, some scientists have discovered that dwarf planets in our solar system are underestimated, and that they may have some conditions for habitability, such as the notorious Ceres.

In mid-2020, as many as seven papers related to Ceres were published in each of the three major journals of the journal Nature. The papers were based on data from the Dawn probe, which provided an in-depth analysis of Ceres. In their analysis of Ceres, the researchers found some special areas on its surface where liquid water and even life may exist. So what exactly did Dawn find on Ceres? What are some of its surprising manifestations?

What is a dwarf planet?

Before 2006, the concept of a "dwarf planet" did not exist in the astronomical community, and it was only thanks to the controversy over Pluto that scientists revisited the definition of Pluto. At the International Astronomical Union in 2006, many scientists voted to remove Pluto from the list of planets. In the end, Pluto was downgraded to a "dwarf planet" because it was too small and too massive to clear its orbit of other objects.

As the nine planets of the solar system became history, the astronomical community came up with a new definition of a dwarf planet, i.e. a planet that is between a planet and an asteroid in size, can revolve around a star, and is massive enough to make its shape almost spherical, but cannot clear other objects in its orbit. After this definition was proposed, some planets were downgraded, while others were "promoted", such as Ceres, located between Mars and Jupiter.

The main characteristic of dwarf planets is that their mantle and crust are made of a mixture of ice and gaseous elements, and although some heavy element compounds are present, they do not account for a high percentage of the total density of dwarf planets. The largest dwarf planet in our solar system is Pluto, which has a diameter of 2370 km, and the smallest dwarf planet is Cajun, which is about 800 km in diameter. Ceres is closer to the Sun than Cajun or Pluto, and therefore Ceres is thought to have water on its surface.

How did humans discover Ceres?

Most discoveries of objects in our solar system have been made through observations, but the discovery of Ceres is unique in that it was first conjectured mathematically and then confirmed by astronomers through observations. The discovery of Ceres began in 1766, when a German mathematics teacher, Johann Ditis, who liked to study number sequences, discovered by chance that the numbers in a set of sequences were related to the distances of the planets from the Sun.

At that time, the man had already discovered four rocky planets and two gas giants, and Doughty discovered by looking through the data that the distance of each of the six planets to the sun was proportional to the numbers in the series, but he found that there was an extra number in the middle of the numbers representing Mars and Jupiter. So Thracius told his astronomer friend about this discovery, and his friend speculated that there should be an undiscovered planet between Mars and Jupiter.

Astronomers then tried to observe the region between Mars and Jupiter with astronomical telescopes, but long observations did not yield the expected results. It was not until 1801 that the Italian astronomer Piazzi while observing the universe with his telescope, discovered a special bright spot between Mars and Jupiter. Just as Piazzi was planning to make a long-term follow-up of the planet, he fell ill. When his body recovered, he found that the bright spot had disappeared.

Piazzi was so sure that what he saw at that time was a celestial body, so many astronomers and astronomy enthusiasts believe Piazzi, also joined the search for the "bright spot planet". Finally, on the last night of 1801, an astronomy enthusiast in Germany discovered the bright spot that Piazzi had described. After several astronomers identified the bright spot as a planet, it was later known as Ceres.

What did Dawn find on Ceres?

Dawn is a space probe developed by NASA, it is the first probe in human history dedicated to detecting the asteroid belt, successively detecting the two largest objects in the asteroid belt - Ceres and Vesta. It is understood that the Dawn program cost a total of about $357 million, it was officially launched on September 27, 2007, at the Kennedy Space Center in Florida, and after eight years of flight finally entered the intended orbit of Ceres.

The main reason why NASA launched Dawn to explore Ceres and Vesta is that Vesta is a rocky planet similar to Earth and Ceres is a typical frozen object, but both planets can surprisingly be in the asteroid belt at the same time. Also, because both Ceres and Vesta were redefined as dwarf planets after the 2006 IAU, which aroused NASA's interest in exploring them, what did Dawn find in the process of exploring Ceres?

In 2017, the American journal Science published a scientific report from NASA that indicated that the Dawn probe may have found carbon-based organic compounds on Ceres. It is known that all life on Earth is carbon-based, so the presence of carbon-based organic compounds implies the existence of life or the possibility of breeding life. The report states that Dawn has found traces of organic compounds in a crater in Ceres' northern hemisphere.

Although NASA scientists say they have not been able to determine the molecular structure of the organic compound, what is certain is that it is similar to asphaltite. The discovery comes on the heels of a special photo taken by Dawn in 2015 after it entered Ceres' orbit and sent it back to Earth's control center. The photo showed a bright patch on a region of Ceres' surface, and the brightness emitted by the region varied randomly when facing the Sun.

What does the discovery tell us?

And what is the true identity of this bright spot? By analyzing the data returned by Dawn, NASA scientists determined that the bright spot is located in the Okato crater region, and by analyzing Ceres' crust, speculated that the bright spot could be a salt deposit. This means that there may be a brine reservoir underneath Ceres, so why would the brine layer dissipate to the surface? In this regard, some scientists believe that a small celestial body impacted Ceres, causing the surface layer to interoperate with the subsurface layer, and the brine gushed out of the surface.

Since Ceres has no atmosphere and the average temperature is below zero degrees Celsius, the brine flowing out of the surface quickly turned into ice crystals. This speculation was shared by most NASA scientists, so they continued to deconstruct and analyze Dawn's probe data the following year, and found that Ceres' crust has a low density, which proves that its crust is not primarily made of rock, but probably ice or a mixture of ice and other materials.

What does this tell us? Geologists believe that the structure of Earth's early oceans may have been similar to that of Ceres, in that there was a subsurface brine layer, and then the brine layer came to the surface after an impact from an alien body, gradually forming an ocean. Ceres have shown similar signs, but because of the lack of atmospheric protection, the liquid material that came out of the ground could not continue to maintain its liquid form. Some scientists believe that if Ceres is closer to the Sun, it may appear as an ocean.

Could Ceres "come later"?

There has been only one planet that could enter the discussion of human migration bases, and that is Mars. Since the U.S. exploration of Mars in the 1970s, humans have gradually seen the "true face" of the planet. Mars is not as beautiful as originally thought, but its natural environment is not as bad as other planets, so scientists have not given up on its exploration, and the United States has even publicly said to achieve the Mars migration by 2050.

So apart from Mars, no planet can be included in the discussion? Exploration in recent years has shown that Io, Titan, and Ceres are all possibilities, with Ceres being the closest of the three planets to Earth. For Ceres, scientists at the American Institute of Planetary Science say that although Ceres is an unnamed dwarf planet, it may not be worse than other planets in terms of habitability, because Ceres has certain advantages in the conditions needed for life to survive.

It is still too early to conclude Ceres, but humans need to send a probe to land on Ceres and then explore the planet's surface as they did on the surface of Mars.

Is there a "spring" for dwarf planets?

It is believed that the reason why Ceres and Vesta have attracted more human attention is that Pluto was downgraded to a "dwarf planet", and in 2006 the Astronomical Union redefined Pluto, introduced the concept of the dwarf planet, and redefined Ceres and Vesta as dwarf planets. Since then, not only has Pluto received more attention than it originally did, but several astronomy enthusiasts still hold out for Pluto, arguing that it should be a planet rather than a dwarf planet.

And Ceres and Vesta have also received more attention, and NASA has dedicated a plan to explore these two dwarf planets, which has indeed been carried out since then. Humans have given more attention to dwarf planets, which means that the veil of dwarf planets will be taken off layer by layer. By exploring and studying them, scientists may make discoveries that will be beneficial to human interstellar migration in the future. Thus, the "spring" of dwarf planets is coming.