Hubble dazzles with young stars in Trifid Nebula for 36th anniversary

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The colours in Hubble’s visible light image of this shimmering region of star-formation are reminiscent of an underwater scene filled with fine-grained sediments fluttering through the ocean’s depths.

A tightly cropped Hubble view of a vast star-forming region known as the Trifid Nebula. The top left is bright blue. Brown and amber colours run from top right through the center in irregular, overlapping lines to the bottom-center. At bottom right, the view is almost black. Tiny, amber-coloured stars appear throughout the scene. Toward the left there is a prominent brown shape that looks like a head with two horns. The left horn points left and is wavy. The right horn is triangular and points up. The brown dust continues, flowing down, as if along a back, and up toward the top right. A prominent line, about the same length as the left horn, appears below the middle of the body, and changes from orange to red. A small, separate semi-transparent pillar is left of the head. A few slightly larger, blue foreground stars with four diffraction spikes appear in the bottom half. Image credit: NASA, ESA, STScI. Image processing: J. DePasquale (STScI)

Several massive stars, which are outside this field of view, have shaped this region for at least 300,000 years. Their powerful ultraviolet winds continue to blow an enormous bubble, a small portion of which is shown here, that pushes and compresses the cloud’s gas and dust, triggering new waves of star formation.

A ground-based photo of the full Trifid Nebula is shown on the left half with an inset image from the Hubble Space Telescope at right. At left, an irregular mostly opaque circle takes up the majority of the view. The circle has a bright pink interior crossed with a few dark, jagged dust lanes. A significant region around that appears blue. The edges have shades of orange and brown, with the star-filled black background of space peeking through. Hubble’s close-up is outlined just below center to the left. The top left is bright blue. Brown and amber colours run from top right through the center in irregular, overlapping lines to the bottom-center. At bottom right, the view is almost black. Tiny, amber-coloured stars appear throughout the scene. Toward the left there is a prominent brown shape that looks like a head with two horns. Image credit: NASA, ESA, STScI. Image processing: J. DePasquale (STScI)

This isn’t the first time Hubble has gazed at this scene. The telescope observed the Trifid in 1997 and now, 29 years later, it has leveraged almost its full operational lifetime to show us changes in the nebula on human time scales. Why look at the same location again? In addition to seeing changes over time, Hubble is also equipped with an improved camera with a wider field of view and greater sensitivity that was installed during the fourth servicing mission.

Star formation in the ‘Cosmic Sea Lemon’
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Hubble’s view of the Trifid Nebula (also known as Messier 20 or M20) focuses on a “head” and undulating “body” of a rusty-coloured cloud of gas and dust that resembles a marine sea lemon, or sea slug, that appears as if it is gliding through the cosmos.

A star-forming region is blue at top left, brown and amber from top right to bottom center, and black at bottom right. Tiny, amber-coloured stars float throughout. Toward the left there is a brown shape that looks like a head with two horns. A label, HH 399 jet, marks the left horn. A second label, possible counter jet, marks a redder area within the “body” of brown dust. Below the title is a colour key showing which WFC3 filters were used to create the image and which visible-light colour is assigned to each filter. From top to bottom: F475W (light blue), F502N (blue), F656N (green), F673N (red), F814W (orange). At the bottom left is a scale bar labeled 1 light-year, 42 arcsec. The length of the scale bar is about one fourth of the image. At the bottom right are compass arrows indicating the orientation of the image on the sky. The east arrow points toward 7 o’clock. The north arrow points toward 10 o’clock. Image credit: NASA, ESA, STScI

*The Cosmic Sea Lemon’s left “horn” is part of Herbig-Haro 399, a jet of plasma periodically ejected over centuries by a young protostar[^] [1] embedded in the head of the sea lemon. Watch the jet expand. Changes observed allow researchers to measure the speeds of the outflows and determine how much energy the protostar is injecting into these regions. The measurements will provide insights into how newly formed stars interact with their surroundings.

To the immediate lower right is evidence of the counter jet: jagged orange and red lines that ”run” down the back of the sea lemon’s neck, where a natural V appears in the brown dust.

The darker, more triangular “horn” on the right of the “head” hosts another young star at its tip. Zoom in to see a faint red dot with a tiny jet. The green arc above it may be evidence that a circumstellar disc is being eroded by the intense ultraviolet light from nearby massive stars. The clearer the area around this protostar suggests it may be almost finished forming.

To the immediate left of the Cosmic Sea Lemon is a small, faint pillar. Much of this pillar’s gas and dust has been blown away, but the densest material at the top persists.

The colours in this image from the NASA/ESA Hubble Space Telescope tell a story about density in the Trifid Nebula, a star-forming region about 5000 light-years from Earth. The top left, where it is bright blue, has the smallest amount of dust. Here, powerful ultraviolet light stripped electrons from nearby gas, creating a glow, with winds creating a bubble by clearing out surrounding dust.

An example of active cloud destruction is toward the top of the head-shaped area with two “horns.” Bright yellow gas streams upward where gas and dust are being destroyed.

Thicker dust appears dark brown, like mud. In the far-right corner, which is nearly pitch black, the dust is the densest.

Fully formed stars — bright orange orbs — are scattered across the scene. Their light and stellar winds have also cleared the immediate areas around them.

Over millions of years, the gas and dust that make up this nebula (also known as Messier 20 or M20) will disappear and only stars will remain.

Credit: NASA, ESA, STScI, N. Bartmann (ESA/Hubble). Music: Stellardrone - Ascent

Streaks and sharp lines offer more clues about other young stars’ activities. Spy an example by looking near the center for a rippling angled line that begins in a bright orange and ends in a blazing red. In the image comparison, it appears to move, which means it may be a jet shot out by another actively forming star buried deeply in dust.

This Space Sparks episode highlights a variety of images that have been featured throughout Hubble’s 36th year of operations.

Prismatic ‘sea’ of colour
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In Hubble’s visible light observations, the clearest view is toward the top left, where it’s bluer. Strong ultraviolet light from massive stars, not in the field of view, stripped electrons from nearby gas, creating a glow, with winds sculpting a bubble by clearing out surrounding dust.

At the top of the Cosmic Sea Lemon’s head, bright yellow gas streams upward. This is an example of ultraviolet light plowing into the dark brown dust, stripping and dismantling the gas and dust.

Many ridges and slopes of dark brown material will remain for a few million years, as the stars’ ultraviolet light slowly eats away at the gas. The densest areas are home to protostars, which are obscured in visible light.

The far-right corner is nearly pitch black. This is where the dust is the densest. The stars that appear here may not be part of this star-forming region — they might be closer to us, in the foreground.

This Space Sparks episode highlights science discoveries published throughout Hubble’s 36th year of operations. Credit: NASA, ESA, STScI, N. Bartmann (ESA/Hubble), M. Zamani (ESA/Hubble), D. Bodewits (Auburn), J. DePasquale (STScI), B. Balick (University of Washington), G. Anand (STScI), and A. Benitez-Llambay (Univ. of Milan-Bicocca), D. O’Ryan, P. Gómez (European Space Agency), R. Crawford (STScI), D. Li (Utoronto), W. Blair (JHU). Music: Stan Dart - Organic Life

Now, scan the scene for bright orange orbs. These stars have fully formed, clearing the space around them. Over millions of years, the nebula’s gas and dust that make up the nebula will disappear — and only stars will remain.

Unprecedented longevity, nonstop discoveries
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Hubble’s varied instruments and the expansive range of light it collects — from ultraviolet to near-infrared — have helped researchers make ground-breaking discoveries for decades and supply new data daily that will inevitably lead to more.

“Fly” through the NASA/ESA Hubble Space Telescope’s view of the Trifid Nebula. The video “floats” over the ridges of gas and dust and moves up toward Herbig-Haro 399, at the top of a brown cloud that resembles a head with horns.
The thinner, irregular line pointing left formed from the ejections of an actively forming star.
To its left is a small, faint pillar. Much of this pillar’s gas and dust has been blown away, but the densest material at the top persists. Credit: NASA, ESA, STScI, Leah Hustak (STScI), Christian Nieves (STScI). Image Processing: J. DePasquale (STScI), A. Pagan (STScI). Contributors: Subaru Telescope, R. Gendler. Acknowledgement: G. Bacon (STScI), J. Muzerolle (STScI), F. Summers (STScI)

In the last year, Hubble has enabled discoveries ranging from a relic of early galaxy formation, to a galaxy so faint it’s nearly invisible, to unknown cosmic anomalies found with the help of AI. Researchers spotted asteroids colliding in another star system for the first time, while in our own Solar System Hubble serendipitously captured a comet breaking up. The long-held prediction that our Milky Way galaxy will collide with Andromeda in the distant future was challenged by a new study, using data from Hubble and ESA’s Gaia. Hubble also tracked the interstellar comet 3I/ATLAS https://www.esa.int/Science_Exploration/Space_Science/ESA_observations_of_interstellar_comet_3I_ATLAS that unexpectedly appeared in the Solar System last year, contributing with a rapid estimation of its size.

Hubble’s 36th year of operations has also brought more impressive views of the cosmos. Among these were the star-forming region N11 in the Large Magellanic Cloud, the shells of stardust that make up the Egg Nebula, the Cat’s Eye Nebula together with ESA’s Euclid, and a brand-new image of the famous Crab Nebula. Hubble also showcased the smouldering heart of M82, swirling spiral galaxies UGC 11397 and Arp 4, dust rings around galaxy NGC 7722, the glittering stars of globular cluster NGC 1786, and the immense galaxy cluster Abell 209.

The telescope has taken over 1.7 million observations to date. Almost 29 000 astronomers have published peer-reviewed science papers using Hubble data collected over the telescope’s 36-year lifetime, resulting in more than 23 000 publications, with almost 1100 in 2025 alone. Since 2022, researchers have regularly combined Hubble’s observations with those from the James Webb Space Telescope to push opportunities for discovery further.