A Guide to Cosmic Temperatures

Explore the temperatures of the cosmos, from absolute zero to the hottest temperatures yet achieved, with this infographic. Targets for the XRISM mission include supernova remnants, binary systems with stellar-mass black holes, galaxies powered by supermassive black holes, and vast clusters of galaxies.

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

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Horizontal version of the above.

Credit: NASA's Goddard Space Flight Center/Scott Wiessinger

Just slightly warmer than absolute zero is the Resolve sensor inside XRISM, pronounced “crism,” short for the X-ray Imaging and Spectroscopy Mission. This is an international collaboration led by JAXA (Japan Aerospace Exploration Agency) with NASA and ESA (European Space Agency). Resolve operates at one twentieth of a degree above 0 K. Why? To measure the heat from individual X-rays striking its 36 pixels!

Credit: NASA’s Goddard Space Flight Center

Alt Text: Cartoon of JAXA’s XRISM telescope gently rocking and back and forth on a dark blue background. The spacecraft has a roughly cylindrical body, which is depicted in light blue with various hardware shown as gray lines and shapes. Solar array "wings" extend on either side and a smaller, rounded cylindrical section pointing toward the right has small tubes extending from the end. Text above reads “XRISM’s Resolve sensor,” and text below says “0.05 K, -459.58°F (-273.10°C).”

The Boomerang Nebula is the coldest known region in the cosmos at just 1 K on the Kelvin temperature scale that astronomers use (learn more about it at the link in the first post). This cloud of dust and gas left over from a Sun-like star is about 5,000 light-years from Earth.

Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

Alt Text: Cartoon of the Boomerang Nebula subtly shifting on a dark blue background. The nebula is depicted as layered blobs in different shades of pink. A small light pink oval is near the center, and the entire nebula is speckled with small white dots. Text above reads “Boomerang Nebula,” and text below says “1 K, -457.9°F (-272.2°C).”

Icy gas giant Neptune is the coldest major planet in our Solar System. It has an average temperature of 72 K at the height in its atmosphere where the pressure is equivalent to sea level on Earth.

Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

Alt Text: Cartoon of Neptune against a dark blue background. The planet is mostly a medium shade of blue with streaks of lighter and darker blues. Text above reads “Neptune,” and text below says “72 K, -330°F (-201°C).”

Bringing things closer to home, according to NOAA, Death Valley set the world’s surface air temperature record on July 10, 1913. This record of 330 K has yet to be broken — but recent heat waves have come close.

Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

Alt Text: Cartoon of Death Valley in an oval inside a dark blue background. A yellow sun slowly sets in a golden sky behind abstract dark brown mountains. Text at the top of the scene reads “Death Valley,” and text below says “330 K, 134°F (56.7°C).”

Earth’s inner core is a solid sphere made of iron and nickel that’s about 760 miles (1,220 kilometers) in radius. It reaches temperatures up to 5,600 K.

Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

Alt Text: Cartoon of Earth against a deep purple background. The surface of Earth shows royal blue water and the green shapes of landforms. A triangular wedge has been removed from the side facing us, revealing the layers inside. The innermost layer is a blazing white, followed by yellow, orange, and red as they near the surface. Text above reads “Earth’s core,” and text below says “5,600 K, 10,000°F (5,300°C).”

We might assume stars would be much hotter than our planet, but the surface of Rigel is only about twice the temperature of Earth’s core at 11,000 K. Rigel is a young, blue star in the constellation Orion, and one of the brightest stars in our night sky.

Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

Alt Text: Cartoon of Rigel and the constellation Orion against a deep purple background. On the right is a glowing light blue star with a slightly mottled surface that slowly spins. To its left is a pattern of dots connected with lines, showing the shape of Orion, which very loosely resembles a human with a bow. Rigel’s location is marked in the lower right of the constellation and connected to the larger star with a translucent triangle. Text above reads “Surface of Rigel,” and text below says “11,000 K, 20,000°F.”

The electrons in hydrogen, the most abundant element in the universe, can be stripped away from their atoms in a process called ionization at a temperature around 158,000 K. When these electrons join back up with ionized atoms, light is produced.

Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

Alt Text: Cartoon of a cloud of ionized hydrogen against a purple background. Concentric magenta blobs fill the center of the image, getting lighter toward the center. A bright white point is slightly right of center, surrounded by a yellow-orange haze and X-shaped spikes of light. Text above reads “Hydrogen ionizes,” and text below says “158,000 K, 284,000°F.”

Our Sun’s surface is about 5,800 K (10,000°F or 5,500°C), but the outermost layer of the solar atmosphere, called the corona, can reach millions of kelvins. Why? This is one of the mysteries that solar scientists have been trying to figure out for years.

Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

Alt Text: Cartoon of the Sun and its corona against a dark purple background. The Sun is a glowing yellow circle at the center, surrounded by wispy white streaks extending outward that gently wave, representing the corona. Occasionally, smaller white filaments travel inward or outward along very subtle white lines that curve around the Sun, depicting its magnetic field. Text above reads “Solar corona,” and text below says “3 million K, 5.4 million°F.”

Located about 240 million light-years away, the Perseus galaxy cluster contains thousands of galaxies. It’s surrounded by a vast cloud of gas heated up to tens of millions of kelvins that glows in X-ray light.

Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

Cartoon of a galaxy cluster against a bright purple background. The cluster is depicted as a dozen orange and yellow ovals and abstract spiral galaxies within a cloud in shades of brown with a small tan blob at its center. Text above reads “Perseus galaxy cluster,” and text below says “50 million K, 90 million°F.”

When massive stars — ones with eight times the mass of our Sun or more — run out of fuel, they put on a show. On their way to becoming black holes or neutron stars, these stars shed their outer layers in a supernova explosion. These layers can reach temperatures of 300 million K!

Credit: NASA’s Goddard Space Flight Center

Alt Text: Cartoon of layers of material slowly expanding after a supernova explosion against a bright purple background. A bright central dot represents the exploding star, which is surrounded by concentric spiky layers in different shades of pink and purple. Text above reads “Supernova shell,” and text below says “300 million K, 550 million°F.”

When stuff gets too close to a black hole, it can become part of an orbiting debris disk with a conical corona swirling above it. This hot environment, which can reach temperatures of a billion kelvins, helps us study black holes even though they don’t emit light themselves.

Credit: NASA’s Goddard Space Flight Center/Jeremy Schnittman

Alt Text: Cartoon of material swirling around a black hole, our view distorted by strong gravity, against a deep purple background. The center of the image is a black hole, with a thin ring of orange around it, then a small gap, and then a striped disk of material. The disk in front of the black hole appears as we would expect, with the disk arcing in front of the black hole like a flat pancake. However, the far side of the disk is visible above and below the black hole, instead of being blocked by it. This is due to the black hole’s gravity, which redirects the light on its path to us. Text above reads “Black hole corona,” and text below says “1 billion K, 1.8 billion°F.”

Just one second after the big bang, our tiny, baby universe consisted of an extremely hot — around 10 billion K — “soup” of light and particles. It had to cool for a few minutes before the first elements could form.

Credit: NASA’s Goddard Space Flight Center/CI Lab

Alt Text: Cartoon of the moments of the universe after the big bang, against a pinkish-purple background. A blazing blob of white fills the center of the image, surrounded by a halo of bright pink, with spikes of magenta extending in all directions. Text above reads “Universe's first second,” and text below says “10 billion K, 18 billion°F.”

Scientists use the Large Hadron Collider at CERN to smash teensy particles together at superspeeds to simulate the conditions of the early universe. In 2012, they generated a plasma that was over 5 trillion K, setting a world record for the highest human-made temperature.

Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

Alt Text: Cartoon of a plasma formed within CERN’s Large Hadron Collider, against a purple background. A blue spherical cloud slowly expands at the center of the image, electric blue on the outside and a deeper blue at the center. Blue lines and dots surround this cloud, moving outward as it becomes larger. Text above reads “Large Hadron Collider,” and text below says “5.5 trillion K, 9.9 trillion°F.”