Following the wanderers of Orion

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Following the wanderers of Orion

Published: 27 Mar. 2025, 00:05

Audio report: written by reporters, read by AI

Ko Jae-hyun

The author is a professor at the School of Semiconductor and Display Engineering, Hallym University.

On winter nights, Orion often appears above the southeastern rooftops. The three stars aligned at the center — recognized by the Greeks as the hunter’s belt — are the constellation’s most iconic feature. As familiar as it is to the naked eye, Orion is also a fascinating subject for astronomers. Among its many wonders, the Orion Nebula — where young stars are being actively born — serves as a natural laboratory for uncovering the secrets behind the formation of stars and planets. Does nature only reveal its mysteries to those who are prepared to seek them? In this cosmic cradle, the James Webb Space Telescope, the most powerful observatory ever built, recently captured not only the dynamic birth of stars but also hundreds of rogue planets drifting nearby.

Unlike planets like Earth that orbit a star under the pull of gravity, rogue planets are unbound to any single star. They roam the cosmos freely — cosmic nomads untethered from any system.

Since the first confirmed discovery of an exoplanet in 1992 — one orbiting a star beyond our solar system — scientists have identified over 6,000 such worlds. Galaxies brimming with stars, it turns out, are also overflowing with planets. But beginning in the early 21st century, astronomers began to detect an entirely different kind of world: the rogue planet. Estimates now suggest that our Milky Way alone may host tens of billions — or even trillions — of these lonely wanderers. The universe, then, is not only a realm of stellar families but also a vast stage for solitary travelers.

The image of the Orion Nebula taken by the Advanced Camera for Surveys (ACS) aboard NASA/ESA Hubble Space Telescope. More than 3,000 stars of various sizes appear in this image. [NASA, ESA, CSA]

Today, astronomers are able to observe the weather patterns of massive rogue planets and, using Albert Einstein’s general theory of relativity, have even begun detecting Earth-sized ones. If NASA’s Roman Space Telescope, scheduled for launch in 2027, succeeds in its mission to discover hundreds of Earth-like rogue planets, it could provide vital clues to the number of such planets in the galaxy and the underlying principles of planetary formation.

In the past, looking up at Orion evoked visions of radiant nebulae glowing with the energy of newborn stars, and of planets taking shape within the swirling disks around them. These days, Orion brings to mind the solitude of planets that have found no home. What secrets might these cosmic vagabonds reveal to humanity? The 21st century is shaping up to be the era in which humankind begins to decipher the grand epic of the universe anew.

Translated using generative AI and edited by Korea JoongAng Daily staff.