NASA provides a time-lapse movie showing how the universe has changed over 12 years

The universe is over 13 billion years old, so a 12-year slice of that time may seem uneventful. But a NASA time-lapse movie shows how much can change in just over a decade. Stars pulsate, asteroids follow their orbits, and distant black holes glow while attracting gas and dust.

NASA launched WISE – the Widefield Infrared Survey Explorer – in 2009. Among other things, WISE found star clusters, thousands of dwarf planets and helped discover Earth’s Trojan asteroids. When WISE ran out of primary coolant in 2011, NASA put the spacecraft into hibernation. But some of the spacecraft’s infrared detectors were still working. In 2013 they reactivated the mission as NEOWISE – Near-Earth Object Wide Field Infrared Survey Explorer. One of NEOWISE’s main goals was to characterize 2,000 known asteroids.

The spacecraft did these things by taking long-range surveys of the sky. Every six months, NEOWISE creates an image of the night sky. NASA combined 18 of these all-sky images, taken over a decade, to create a time-lapse of the night sky. Together they contain hundreds of millions of objects.

“When you go outside and look at the night sky, it seems like nothing ever changes, but that’s not the case,” said Amy Mainzer, principal investigator for NEOWISE at the University of Arizona in Tucson. “Stars shine and explode. Asteroids whiz by. Black holes tear stars apart. The universe is a really busy, active place.”

One of the mission’s significant contributions to science is the study of brown dwarfs. Brown dwarfs are not really stars; they are substellar objects on the way to becoming stars. But they never accumulated enough mass to trigger hydrogen fusion. They are smaller than stars and larger than the largest planets. Their masses range from about 13 to 80 Jupiter masses.

Astrophysicists theorized that brown dwarfs existed, but only infrared observations could find them. Infrared astronomy is difficult from the surface, although the 2MASS survey has successfully found some. Thanks to infrared observatories like WISE/NEOWISE, we now know thousands of them.

Astrophysicists are interested in the coolest brown dwarfs because they bridge the gap between stars and planets. They are brown dwarfs of spectral class Y and emit very little energy. The coolest are just above room temperature. WISE discovered the Y-class brown dwarfs in 2011.

NASA eventually combined data from WISE and NEOWISE into a catalog called CATWISE. In 2019, scientists searching the catalog CWISEP found J1935-1546, an even colder brown dwarf with an estimated temperature of 270–360 K (?3–87 °C; 26–188 °F).

Citizen scientists have also played a role in NEO/NEOWISE’s brown dwarf activities. Citizen Scientists helped find two of the most unusual brown dwarfs ever found. They are called T-type sub-dwarfs and scientists and volunteers found them in 2020 as part of the Backyard Worlds project.

In 2020, scientists collaborating with NEOWISE discovered the strangest brown dwarf yet. They called it the “accident” because they found it accidental. The accident is ancient – between 10 and 13 billion years old – and has very low metallicity. It is so old that its metallicity reflects the early universe rather than the modern universe. Generations of stars have created heavier elements and dispersed them in space over billions of years, so objects that formed more recently have higher metallicity.

Although the accident is the first of these ancient brown dwarfs ever found, it likely won’t be the last. Many of them are probably lurking in the dark, maybe even still hiding in NEOWISE data.

The NEOWISE mission took much longer than expected. When NASA launched it as WISE, they figured it would be about two years before it ran out of coolant. But after recommissioning as NEOWISE, the mission has been running for ten years. Even WISE scientists are surprised by the length of the mission and the amount of data collected.

“We never expected the spacecraft to be operational for so long, and I don’t think we could have anticipated the science that we could do with so much data,” said Peter Eisenhardt, astronomer at NASA’s WISE Jet Propulsion Laboratory -Project Scientist.

If you’re interested in helping scientists harness all of the data from NEOWISE and maybe even find one of the elusive, ancient brown dwarfs like The Accident, check out Backyard Worlds: Planet Nine.