Scientists have found a bunch of homeless planets in our galaxy. These are rogue planets, planets that orbit galaxies with no parent stars.
Conventionally, a planet refers to a celestial body that elliptically orbits the sun or any other star. However, this holds to a great extent until an anomaly presents itself. The oddity becomes noticeable with a group of planets that do not orbit stars, and therefore transit the Milky Way galaxy on their own. Scientists also refer to them as rogue, nomads, and freely-floating planets.
Researchers estimate the number of these wandering planets in our galaxy to be 100,000 times more than stars in the Milky Way. Still, the fundamental questions revolve around their formation, detection, unique properties, and, importantly, future studies.
To begin with, it is crucial to understand that the formation of the homeless planets, just like Earth, involves debris left over after the birth of a star. The debris orbit the young star in the form of grains and gas, growing steadily in size as these materials clump together.
This Article In Video: A Bunch Of Homeless Planets Found In Milky Way
Stars do not form singularly. Thus, the impact between their developing planetary systems results in chaotic activity.
On collision, two or more proto-planets gradually chip away from each other to form either other bodies in the galaxy like the moon or, in the case of homeless planets, being knocked out altogether into the vast and cold space in the middle of stars. These are the “rogue” or homeless planets.
This concept disrupts the whole idea that previously existed. Therefore, it becomes necessary to have a way to detect these planets comprehensively.
In most cases, astronomers rely on the influence planets have on the stars they orbit to detect them. This is a no-brainer in this case since the planet has no parent star. Also, it is impossible to see the planet directly because it doesn’t emit light, further complicating the process. How, then, can we detect these planets?
What is gravitational microlensing?
This is by far the best method for the discovery of far-off planets. To break it down, microlensing refers to the ability of a star in the foreground to temporarily magnify the light coming from a background star, eventually culminating in bursts in brightness that telescopes can observe. This idea borrows heavily from Einstein’s General Theory of Relativity.
As we know, mass always bends space, and as a result, we can witness the bending of starlight from the background to the foreground—in the case of a rogue planet, the light takes a different path. For example, if we implement the working principle of a magnifying glass when an object in space goes between a star and Earth, the star flares up when the object passes.
By estimation, microlensing affects about a million stars in the Milky Way, while planets cause lesser.
In furtherance of evidence collection on floating planets, the Kepler Space Telescope played a considerable role in bringing to the fore, in terms of fractions, the number of planets in the Milky Way that had a size close to that of Earth and appeared in the habitable zone. Scientists put this off in 2016 after observation of close to 200,000 stars and the telescope developing technical problems.
In the same year, the K2 Mission was launched. And in four months, it had uncovered millions of gravitational microlensing events by monitoring stars at our galaxy’s core.
Recently, four homeless rogue planets with Earth-mass were discovered using data obtained from the K2 Mission phase of the Kepler Space Telescope, that is has been long dead notwithstanding.
The researchers found about 27 faint signals ranging from an hour to 10 days consistent with the expected results. For now, the specific characteristic of these planets remain unknown, and surface options ranging from icy, rocky to gas cannot be precluded.
Finally, the future of these planets, and microlensing by extension, is buzzing with excitement.
Two exciting missions a few years apart herald the future as far as the study and development of this field is concerned. First, European Space Agency’s EUCLID satellite will launch in mid-2022. It will help map the universe’s geometry and employ the use of the microlensing technique in searching for exoplanets. Second, the Nancy Grace Roman Space Telescope will launch in 2025 with the primary goal of surveying distant stars.
Scientists published their results in Nature.