Hubble’s 36‑year celebration: a fresh view of M20
On the anniversary of the launch of the Hubble Space Telescope, astronomers have released a breathtaking picture of the Trifid Nebula (Messier 20). The image, captured with the Wide Field Camera 3, revisits the same patch of sky first photographed in 1997, allowing a direct comparison that shows the nebula’s evolution over human timescales.
What makes the Trifid Nebula special?
Located roughly 5,200 light‑years away in the constellation Sagittarius, the Trifid is a rare hybrid of emission, reflection and dark nebulae. Its name derives from the Latin “trifidus”, meaning split into three, which describes the three dark dust lanes that carve the glowing gas into distinct lobes.
A cosmic “sea lemon” and a shifting jet
The new picture reveals a rosette‑shaped cloud that the Hubble team nicknamed the “Cosmic Sea Lemon”. Dark brown filaments wind around a bright orange core, while a brilliant blue region marks the most transparent part of the nebula, bathed in ultraviolet radiation from massive newborn stars.
Most striking is the displacement of the stellar jet known as HH 399. In the 1997 exposure the jet’s tip lay at a certain position; in the 2026 frame it has moved noticeably in just 29 years. This shift allows astronomers to calculate the outflow speed and the energy injected by the still‑forming protostar that powers it.
Comparing two generations of Hubble
The legacy camera that filmed the original scene, WFPC2, produced a landmark image that has been reproduced countless times. The upgraded Wide Field Camera 3 not only delivers higher resolution, but also captures fainter structures such as a possible counter‑jet and a second, red‑tinged outflow hidden deep within the dust.
Beyond the visual spectacle, the data provide a rare laboratory for studying star‑formation dynamics on timescales that are normally far beyond the reach of human observation.
Why it matters
Marking more than three decades of service, Hubble continues to push the boundaries of astronomical research. The Trifid comparison underscores how even a “static” sky can evolve perceptibly, reminding us that the cosmos is a constantly changing arena of creation and destruction.
