Stellar Evolution

Stellar Evolution

A colorful nebula with a bright center and symmetrical, wing-like clouds of gas and dust extends outward in space, as seen in a JWST reveal that uncovers stars and galaxies in the universe beyond.
Many facts are well-known to professionals, but are unappreciated or even rejected outright by the public. "How stars work" takes the cake.
Colorful nebula with bright stars ignite glowing gas clouds in space, featuring red, yellow, and blue hues against a dark background.
Although a star's "birth" is well-defined, it doesn't correspond to an ignition event in its core. Here's how stars are actually born.
A bright, circular object with concentric rings and a surrounding halo set against a dark background, resembling a gap-clearing planet or other astronomical phenomena.
One parameter, alone, sets the dividing line between rocky planets, gas giants, brown dwarfs, stars, and much more. Here's why mass matters.
A distorted galaxy with two bright, horizontal bands and scattered stars, seen against a dark background. Image credit: NASA/ESA/CSA.
By looking at a giant, remarkable, edge-on protoplanetary system, astronomers have found a proto-protoplanet for the first time.
A labeled illustration shows the Large Magellanic Cloud, astronomers' most pristine star (SDSS J0715-7334), and the Milky Way galaxy connected by a wispy trail.
The 1st generation of stars formed, lived, and died very early on. But 2nd generation stars could still persist today. Did we just find one?
logarithmic history of universe
In a 13.8 billion year old Universe, a few seconds hardly seems like it matters. But these minuscule changes sure do add up over time.
M81 Group
Over billions of years, fewer stars form, galaxies mutually recede, and the Universe becomes ever darker. Here's how fast it all happens.
Side-by-side images of a nebula in space, showing colorful, wispy gas and dust shells surrounding a bright central region with numerous stars in the background.
Resembling a cosmic brain, the Exposed Cranium Nebula instead shows a dying, massive star, as JWST reveals. Its fate remains uncertain.
A luminous dying sun with jets and swirling clouds appears at the center of a dark background, encircled by concentric patterns—an image reminiscent of Hubble’s stunning cosmic view.
Before Sun-like stars die, they transition from AGB red giants into preplanetary nebulae. Here's how Hubble sees the famous Egg Nebula.
star vs planet vs brown dwarf
13.8 billion years have passed since the Big Bang, but many stars will survive for longer than that. What's the longest-lived a star can be?
A dense field of distant galaxies and bright stars against a black background, as captured in a JWST early galaxies deep space telescope image.
Many collaborations have used JWST to take deep-field images: some wider and some deeper than others. Here's how it can surpass them all.
Green and red aurora borealis lights, sparked by a recent solar radiation storm, arc across the night sky and reflect over a calm lake with a rocky shoreline.
The Sun often produces solar flares and coronal mass ejections, but a rare solar radiation storm made the 2026's first great auroral show.
A vivid image of a galaxy with bright blue and red nebulous clouds, set against a black star-filled background in deep space.
With unprecedented resolution, wavelength sensitivity, and light-gathering power, JWST reveals our cosmos like no other observatory ever.
Five panels show NASA Chandra images of Kepler's supernova remnant as it expands over 25 years, with increasingly diffuse blue filaments against a starry background; a composite is shown in the last panel.
Back in 1604, Johannes Kepler discovered the Milky Way's last naked-eye supernova. Here's how NASA's Chandra sees it over the 21st century.
Even the youngest galaxies are often dust-rich, even with very low levels of heavy elements. Nearby dwarf galaxy Sextans A explains why.
jwst Abell 2744 450 million
If you can identify a foreground star, the spike patterns are a dead giveaway as to whether it's a JWST image or any other observatory.
Diagram showing light from a distant galaxy bending around a red-hued massive object, reaching telescopes on Earth via different paths and at different times.
With the observation of SN 2025wny, a lensed superluminous supernova, astronomy's future comes into sharp, exciting focus.
Illustration of various carbon molecules, including buckyballs and graphene sheets, floating in space near a bright cosmic background with stars and nebulae.
It takes a wide variety of processes in the Universe to make all the elements that populate space today. We're still discovering new ones!
A bright, circular object with concentric rings and a surrounding halo set against a dark background, resembling a gap-clearing planet or other astronomical phenomena.
Planets grow from protostellar material in disks, leading to full-grown planetary systems in time. At last, the final gap has been filled.
Three side-by-side images show different views of the Red Spider Nebula in space, captured by JWST, with a bright center and colorful gases in orange, green, and blue against a backdrop of stars.
When dying, Sun-like stars have binary companions, spectacular sights arise from the ionization. JWST spots the Red Spider Nebula in action!
star vs planet vs brown dwarf
Red dwarfs are the Universe's most common star type. Their flaring now makes potentially Earth-like worlds uninhabitable, but just you wait.
A colorful, irregular galaxy with bright clusters of stars, some possibly from a generation stars before sun, and nebulae against a dark background scattered with distant stars.
Our Sun only arose after 9.2 billion years of cosmic history: with many stars living and dying first. How many prior generations were there?
ESO milky way
Questions about our origins, biologically, chemically, and cosmically, are the most profound ones we can ask. Here are today's best answers.
A dense star field with dark, irregular dust clouds—where cosmic dust come from—obscures parts of the glowing stars in the Milky Way.
Dust is ubiquitous in the modern Universe, appearing in nearly all galaxies. But our cosmos was born dust-free. So where does it originate?
Side-by-side comparison of the Pismis 24 nebula as seen by Hubble (top left) and JWST (bottom right), with an overlay highlighting image differences.
JWST isn't the first telescope to peer into this factory of star-birth some 5500 light-years away, but its views are the most educational.
An artist's impression of a cluster of stars.
With several seemingly incompatible observations, cosmology faces many puzzles. Could early, supermassive stars be the unified solution?
Four images of a nebula, sculpted by a dead star, are shown side by side in radio, optical, and X-ray wavelengths; the fourth composite image reveals the so-called "Hand of God." Each is labeled at the bottom.
In our own Milky Way, a recently deceased star creates a ghostly, hand-like shape in X-rays some 150 light-years wide. Here's how it's made.
Side-by-side images of the Ring Nebula show its structure in different colors, each with a white dotted oval highlighting the central region.
Our nearby Ring Nebula, with JWST's eyes, shows evidence for planet formation. Will the Sun eventually destroy, and then replace, the Earth?
A dense field of distant galaxies and bright stars against a black background, as captured in a JWST early galaxies deep space telescope image.
Originally, the abundance of bright, early galaxies shocked astronomers. After 3 years of JWST, we now know what's really going on.
the night sky with stars and trees in the foreground.
Looking at a dark, night sky has filled humans with a sense of awe and wonder since prehistoric times. But appearances can be deceiving.