Uranus
is a funny planet. And not just because it has a vaguely innuendo-y name in the
English language. It is absolutely peculiar in its own right. One of its
weirdest features is its tilt. Uranus rotates around the Sun on its side,
with each pole facing the Sun for 42 years before switching. The cause of this
weird tilt has long been suspected to be a collision, and a new study
gives details of the impact.
As
reported in the Astrophysical Journal, an international team used sophisticated simulations to reproduce
what has been observed on the ice giant planet. After using 50 different impact
scenarios, they believe that Uranus was hit by an object roughly twice as
massive as Earth, most likely made of rock and ice. This happened around 4
billion years ago when the Solar System was still quite young.
The
impact didn’t just influence the tilt. The researchers believe that it can
also explain the surprisingly low temperature of the planet. The debris from
the impactor might act as a thermal shield, trapping the heat from the planet's
interior and making the outer atmosphere extremely cold.
“Uranus
spins on its side, with its axis pointing almost at right angles to those of
all the other planets in the Solar System," lead author Jacob Kegerreis, PhD researcher
at Durham University, said in a statement.
"This was almost certainly caused by a giant impact, but we know very
little about how this actually happened and how else such a violent event
affected the planet.