MAR 08, 2019 12:51 PM PST

Exoplanets' Unstable Orbits Could Be Due to Over Tilting

WRITTEN BY: Daniel Duan

An artistic rendition of over-tilting exoplanets (NASA/JPL-Caltech)

For almost a decade, thanks to an increased effort in exoplanet hunting such as NASA's Kepler mission, astronomers have identified a lot of Earth-like planets outside our solar system. However, they had a problem explaining why a significant number of these exoplanets, usually in pairs, have unstable orbits. There seemed to be an invisible force pushing them apart from each other.

A team of Yale researchers thinks they might have found an answer to that mystery: according to their calculation, the pole of these planets could be over-tilted. 

In astronomy obliquity, also known as axial tilt, describes the angle between a body's rotational axis and its orbital axis. All planets exhibit axial tilt to a certain degree. Currently, Earth has an axial tilt about 23°, while the one of Mars is 25°. An oddball in the solar system, Uranus has an axis tilts of 82°, making it look like a tipped-over barrel that rotates on its side.

Related reading: Why Uranus is so tilted?

Scientists had previously suspected that the tides on these planets, caused by their host star, could nudging them out of the regular orbits by draining their orbital energy. But the problem is that later calculation revealed the tides aren't strong enough to pull off such a feat.

Sarah Millholland and professor Gregory Laughlin, the Yale astronomers behind the latest study, added their ingenious tweak to the original theory: they proposed that if these exoplanets have a substantial obliquity, similar to the case of Uranus, then the tides would have sufficient kinetic energy to affect their orbit.

In a press release, Millholland explained their idea: "When planets such as these have large axial tilts, as opposed to little or no tilt, their tides are exceedingly more efficient at draining orbital energy into heat in the planets. This vigorous tidal dissipation pries the orbits apart."
 
The probable over-tilting feature of these exoplanets will have board implications in the planet's physical characters, such as their climate and atmosphere. 

Earth's current obliquity allows our planet to have a gradual switch between distinct seasons. Hypothetically, if a planet has a perfect 90° tilt angle, it would always be summer and day time at one pole, and winter and night time at the other.

And also thanks to the Moon, which has a stabilizing effect on Earth's obliquity, our poles only oscillate in a small range (22°-24°) in the past 5 million years. Otherwise, scientists suspect that Earth's obliquity might reach near 90° over several billion years.

For their next step, the astronomy duo will be looking into the effect of substantial obliquity on planets' structures over time.

Their study was recently published in the journal Nature Astronomy.

What Knocked Over Uranus? And Two Other Mysteries (SciShow Space)

Source: Science Daily

About the Author
  • Graduated with a bachelor degree in Pharmaceutical Science and a master degree in neuropharmacology, Daniel is a radiopharmaceutical and radiobiology expert based in Ottawa, Canada. With years of experience in biomedical R&D, Daniel is very into writing. He is constantly fascinated by what's happening in the world of science. He hopes to capture the public's interest and promote scientific literacy with his trending news articles. The recurring topics in his Chemistry & Physics trending news section include alternative energy, material science, theoretical physics, medical imaging, and green chemistry.
You May Also Like
AUG 18, 2020
Microbiology
The Science of Pesto
AUG 18, 2020
The Science of Pesto
  The word pesto comes from the Genovese word pestâ (pestare in Italian) which means “to pound” o ...
SEP 22, 2020
Chemistry & Physics
New photodectector can see the full light spectrum
SEP 22, 2020
New photodectector can see the full light spectrum
New research from a team at RMIT University highlights the development of a hyper-efficient broadband photodetector that ...
OCT 14, 2020
Chemistry & Physics
The CRISPR Nobel Win from Different Angles
OCT 14, 2020
The CRISPR Nobel Win from Different Angles
CRISPR-Cas9 was THE buzz word in the world of science after the Nobel Chemistry Prize announcement last week. But depend ...
OCT 07, 2020
Neuroscience
Biocompatible Gel Restores Sciatic Nerve Function in Rats
OCT 07, 2020
Biocompatible Gel Restores Sciatic Nerve Function in Rats
Video: Explains poly(lactic-co-glycolic acid), a hydrogel biopolymer that is a similar concept to the new hydrogel built ...
NOV 11, 2020
Chemistry & Physics
Bioconductive ink uses the body's own electrical signals to direct how and where neurons grow
NOV 11, 2020
Bioconductive ink uses the body's own electrical signals to direct how and where neurons grow
The development of a new bioconductive ink from researchers in Australia, India, and Bangladesh is reported in the journ ...
NOV 22, 2020
Chemistry & Physics
New material removes copper ions from wastewater
NOV 22, 2020
New material removes copper ions from wastewater
A promising solution relies on materials that capture heavy metal atoms, such as copper ions, from wastewater through a ...
Loading Comments...