This July 22, the land is running exceptionally faster than usual, making this day one of the shortest ever recorded.
According to the director of scientific content at the Cosmodôme de Laval, Marie-Michèle Limoges, several factors can explain this unusual acceleration.
“Normally, the rotation of the earth slows down. So what we are supposed to observe are longer days, “she explains from the outset, in an interview with” Quebec morning “at LCN on Tuesday.
Indeed, the earth does not turn at a perfectly constant speed, but sometimes its rotation can accelerate, as was the case on July 9, on July 22 and to come on August 5.
The rotation accelerates
However, in recent years, data have been showing an opposite trend: rotation has been accelerating. One of the main reasons is based on the form and the very structure of the planet.
“The earth is not a beautiful completely perfect ball. There are irregularities on the surface. And inside no longer, it is not completely homogeneous, ”says Ms. Limoges, noting that the distribution of the mass influences the speed of rotation of a body.
Added to this are the gravitational effects of the Moon, which exerts a natural brake on earthly rotation by the tidal forces.
«On [la Terre] is in constant interaction with the moon. The earth and the moon attract each other, insists the specialist. This effect, between the earth and the moon, will decrease, slow down the rotation of the earth ”.
However, this slowdown force varies and can be less strong, especially due to the distance from the moon, which is very “distant” from the earth today.
Climate change
According to Marie-Michèle Limoges, climate change could influence the distribution of mass on earth, which can indirectly change the rotation.
“Since 2020, we observe that the rotation of the earth, instead of slowing down, will go and accelerate. […] It has been five years since the rotation of the land accelerated, “notes the director of scientific content at the Cosmodôme de Laval.
Atomic clocks
The acceleration of terrestrial rotation can cause a gap between the time measured by atomic clocks and that dictated by the planet.
“One of the reasons why we also study the rotation of the earth is to know if we have to correct,” explains Marie-Michèle Limoges, noting that scientists can add a second interlayer to the coordinated universal time (UTC) to compensate for a slowdown.
“It is equivalent to stopping clocks, a second to allow the land to catch up,” she continues.
However, if the Earth continues to accelerate, scientists could soon have to withdraw an interlayer second. This discrepancy can lead to “breakdowns” in GPS satellites, telescopes or computer systems, concludes Ms. Limoges.
See the complete interview, above.
