By Nneka Nwogwugwu
Like all the planets, asteroids exist in the heliosphere, the vast bubble of space defined by the reaches of our Sun’s wind. Directly and indirectly, the Sun affects many aspects of existence within this pocket of the universe.
Science direct highlights few of the ways the Sun influences asteroids like the Trojans in our solar system.
The Sun makes up 99.8% of the solar system’s mass and exerts a strong gravitational force as a result.
They are clustered at two Lagrange points. These are locations where the gravitational forces of two massive objects — in this case the Sun and Jupiter — are balanced in such a way that smaller objects like asteroids or satellites stay put relative to the larger bodies.
The Trojans lead and follow Jupiter in its orbit by 60° at Lagrange points L4 and L5.
Sunlight can move asteroids! Like Earth and many other objects in space, asteroids rotate. At any given moment, the Sun-facing side of an asteroid absorbs sunlight while the dark side sheds energy as heat. When the heat escapes, it creates an infinitesimal amount of thrust, pushing the asteroid ever so slightly off its course.
Over millions of years, this force, called the Yarkovsky effect, can noticeably alter the trajectory of smaller asteroids (those less than 25 miles, or about 40 kilometers, in diameter).
Similarly, sunlight can also alter the rotation rate of small asteroids. This effect, known as YORP (named for four scientists whose work contributed to the discovery), affects asteroids in different ways depending on their size, shape, and other characteristics. Sometimes, YORP causes small bodies to spin faster until they break apart. Other times, it may cause their rotation rates to slow.
The Trojans are farther from the Sun than the near-Earth or Main Belt asteroids we’ve studied before, and it remains to be seen how the Yarkovsky effect and YORP affect them.
Source: Science direct
