Mon. Oct 18th, 2021
 
Astrophysicist Solves The Mystery Of How Planets Reflect Sunlight

Astrophysicist Solves The Mystery Of How Planets Reflect Sunlight

In a rare feat, an astrophysicist from the University of Bern, Switzerland, has discovered closed-form solutions – a formula solvable infinite steps – to the century-old problem in astronomy – the relationship between the reflectivity of a planet and its phase curve – the brightness of the planet as a function of the phase angle. The phase angle is the angle between the falling and reflected rays. In the case of observing a planet from Earth, the phase angle is the angle between the sunlight falling on the planet and the reflected light from the planet reaching Earth.

 

Heng’s solutions uncover the relationship between the light reflected by a solar system planet and the shape of its phase curve that only depends upon the angle of scattering – the angle at which the surface of a solar system body scatters sunlight.

Astrophysicist Solves The Mystery Of How Planets Reflect Sunlight

Astrophysicist Solves The Mystery Of How Planets Reflect Sunlight
Astrophysicist Solves The Mystery Of How Planets Reflect Sunlight

 

The research, which Heng produced in collaboration with two other scientists, was published on August 30 in Nature Astronomy.

 

In 1916, an influential American astronomer Henry Norris Russell posed the problem of calculating reflected light from planets in a widely noted paper. According to Russell, the albedo – the percentage of sunlight reflected by a planet -and the phase curves of the planets could tell about their properties. In a paper, Russell also derived the stellar magnitude of the sun, the moon and the planets using their photometric observations. However, he could not find a general solution that could apply to all the bodies equally. In 1981, American lunar astronomer Bruce Hapke came up with an analytic solution to the problem, however, he also could not find a closed-function solution that could simply express the apparent relationship between the albedo and the phase curve, irrespective of the solar system body.

 

Building on the work of the pioneers, Heng’s solutions will offer a long-awaited resolution and help astronomers efficiently analyse decades of data, helping us know more about planets and their moons by just looking at the sunlight they reflect.

Subhangee Guha

Break the Newz.

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