Titan distances itself from Saturn. It does this over a hundred times faster than expected

After many decades of research, measurement and calculations, astronomers have determined that Titan is gradually moving away from Saturn. However, to everyone's amazement, it turned out to be doing it over a hundred times faster than previously thought.

Titan - basic facts

Titan is Saturn's largest moon and the second moon in the solar system after Ganymede. In general, for the moon it is a very unique object. The size alone is not like a typical moon, because it is larger than Mercury, the planet closest to the Sun. What's more, it is the only moon that is covered by a dense atmosphere in which active weather processes occur. However, the most characteristic feature of Titan is that it is the only object in the Solar System outside Earth, on the surface of which there are open reservoirs, lakes and rivers full of water, not liquid methane.

Titan escapes into space

Now, after several dozen years of measurement, scientists have determined that the Titan orbit around Saturn is gradually expanding, which means that this moon is gradually moving away from its home planet. However, the surprise was caused by the fact that Titan escapes more than 100 times faster than expected. Titan's current theory of evolution assumes that he was formed much closer to his planet, but within 4.5 billion years he has moved away from him to the current distance of 1.2 million km (for comparison, the Moon is 380,000 km away from Earth).

Most previous analyzes have indicated that moons such as Titan and Callisto were made more or less where we are currently observing them, 'says Jim Fuller, professor of theoretical astrophysics and author of the latest article describing the evolution of Titan's orbit.

How can the moon run away?

A massive natural satellite orbiting its planet (like the Moon around Earth or Titan around Saturn) exerts a gravitational influence on it, which causes tides (on Earth in the ocean, and in gas Saturn in its gas layers). This creates a gravitational bulge on the surface of Saturn or the Earth's ocean. Due to the fact that the planet rotates around its axis faster than the moon orbits the planet, the resulting "bulge" by gravity over time begins to overtake the moon. Such a pre-bulging bulge also has a gravitational effect on the moon, pulling it toward itself. As a result, the moon is gradually accelerating and thus is moving into ever-wider orbit.

Our moon moves away from the Earth at a rate of 3.8 cm per year. Theories to date have shown that Titan is only 0.1 cm away from Saturn per year, but new calculations clearly contradict this.

The article published in the journal Nature Astronomy described the results obtained by two teams, which for more than 10 years, using various methods, tried to learn the exact orbit of Titan. One of them performed astrometric measurements, i.e. analyzed the position of Titan against the background of stars in the pictures taken by the Cassini probe. The other one using radiometry methods analyzed changes in the Cassini probe speed caused by the influence of Titan's gravity.

Using two independent data sets and two different methods of their analysis, we have obtained results that are mutually compatible - says Valery Lainey, author of the first team from JPL.

Researchers have determined that Titan is moving away from Saturn at a rate of 11 cm per year, which means that in about 5 billion years it will free itself from its gravitational impact and fly away into interplanetary space. On the other hand, there will be no water on Earth for a long time, Mars will have rings, the Sun will start to grow, so basically the Solar System will not resemble itself these days.

Titan distances itself from Saturn. It does this over a hundred times faster than expected