The first green star ever discovered was a white dwarf, which can appear in many colors, despite its name.

The first two white dwarfs were discovered on January 31st, 79 years apart.

You would be crushed almost immediately if you stood on a white dwarf, whose surface gravity is over 100,000 times stronger than Earths.

No black dwarf stars exist, but most of the universe's stars will become one.

White dwarfs are the leftover cores of sun-like stars, which expel their layers after running out of nuclear fuel.

Unlike black holes and neutron stars, white dwarfs are the only major stellar remnant not to form via a supernova.

White dwarfs contain the mass of a star in the volume of a planet, making them too dense to have normal atoms.

Days can be two minutes long on a white dwarf pulsar—a stellar remnant with features that resemble neutron stars.

Research suggests that the small red dots in images of deep space captured by the James Webb Space Telescope since 2022 are black hole stars—black holes surrounded by enormous clouds of gas.

White dwarfs solidify into a diamond-like crystal from the inside out as they cool, according to research and observations.

View the Helix Nebula in different wavelengths of light to identify the structures surrounding the white dwarf.

By separating light with tools such as prisms, scientists can reveal the presence and composition of celestial matter by identifying color fingerprints unique to specific elements and molecules.

View the layers and composition of a white dwarf, including its crystallized core.

White dwarfs stave off gravitational collapse thanks to quantum pressure from electrons, which is limited by special relativity.

Dark energy was discovered using Type Ia supernovae—exploding white dwarfs whose peak brightness can be calibrated to measure distances across the universe.

Brown dwarfs are nicknamed 'failed stars' because, while much more massive than planets, they lack sufficient mass to initiate nuclear fusion in their cores.

While Type Ia supernovae obliterate a white dwarf from the inside, novae can temporarily increase the star's brightness up to 100,000 times without self-destruction.

View a gallery of planetary nebulae—shells of energized gas shed in the formation of white dwarfs.

Some stars take longer to form than the current age of the universe

Unlike most objects, white dwarfs get smaller as they gain mass.

Dark stars are hypothetical stars that would have existed in the early universe

Watch a 3D simulation of a Type Ia supernova, in which carbon fusion completely destroys a white dwarf in seconds.

Ice found in another star system for the first time

Janus is the Roman god of transitions and the nickname for a 'two-faced' white dwarf, featuring hydrogen and helium atmospheres in opposite hemispheres.

The most mysterious (known) star in the universe

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

Solar eclipses block the sun enough to enable scientists to observe its faint outer atmosphere, or corona, whose spectrum led to the discovery of helium over a decade before it was identified on Earth.

In the early 2000s, the average color of the universe was determined by averaging the visible light from 200,000 galaxies, yielding a light beige dubbed 'cosmic latte.'

The edge of the Milky Way may be identified by its star-forming disk

Breaking down sunlight and why the sun appears yellow despite emitting green light the most

View the Crab Nebula in different wavelengths of light to identify the structures surrounding the neutron star—a stellar remnant composed of tightly-packed neutrons.

Within massive clouds of gas and dust called nebulae, many stars often form on short cosmological timescales and collectively orbit one another, creating groups called clusters.

In 1974, a pair of neutron stars provided the first evidence of gravitational waves

The sun is not as exceptional as once believed, but it remains rarer than most stars

By analyzing the color of starlight, astronomers can determine how fast stars within a galaxy are moving toward or away from Earth, revealing the expansion rate of the universe.

Cloud 9 is a dark-matter-dominated failed galaxy

The sun will become a red giant after it exhausts the hydrogen fuel in its core, causing gravity to collapse the core and heat it enough for the surrounding hydrogen shell to ignite, releasing enough energy to cause the star to swell.

Cecilia Payne-Gaposchkin discovered stars are mostly made of hydrogen and helium

Neutron stars, the remains of some massive stars after they explode in a supernova, are the densest directly observable objects in the universe.

Although no such planet exists in our solar system, the most common subtype of exoplanet in the galaxy is the sub-Neptune world, which is larger than Earth but smaller than the ice giants.

An exoplanet detection method involves measuring a host star's auroras

Invisible to direct observation, scientists determined the object at the center of the Milky Way—Sagittarius A*—was a supermassive black hole based on the orbits of fast-moving stars in the area.

Shooting stars are streaks of light produced by meteoroids

Attempts to 'fix' black hole physics have led scientists to theorize new types

Stars hold off gravitational collapse with the energy produced in nuclear reactions in their core, but when massive stars run out of fuel for these reactions, runaway collapse can produce a black hole.

While published images have suggested that Neptune is much bluer than Uranus, the two ice giants are a similarly pale shade of greenish-blue.

Colorizers convert Hubble's gray scale images into color composites of different wavelengths

How a pulsar's properties led to the discovery of the first exoplanets

Watch a simulation of a collapsing star becoming a black hole

Nearly 50 years before the first observational evidence, a soldier fighting on the Eastern Front in World War I found a mathematical solution to Einstein's equations that suggested the existence of black holes.

Through gravitational redshift, light loses energy as it leaves a massive object