The universe comes to life in a slow-motion, all-sky movie based on 14 years of data from NASA’s Fermi Space Gamma Ray Telescope. Our Sun, shining brightly at times, moves carelessly across the sky against the background of high energy sources in our galaxy and beyond.

“The Milky Way’s bright, persistent gamma-ray glow is punctuated by intense bursts of near-light jets that last for several days and are fueled by supermassive black holes in the cores of distant galaxies,” said senior scientist Seth Diegel. The SLAC National Accelerator Laboratory in Menlo Park, California, produced the image. “These dramatic explosions, which can occur anywhere in the sky, occurred millions or billions of years ago, and their light is reaching Fermi as we watch.”

Gamma rays are the highest energy form of light. The film shows the intensity of gamma rays with energies of more than 200 million electron volts detected by the Large Fermi Telescope (LAT) between August 2008 and August 2022. By comparison, visible light has an energy of 2 to 3 electron volts. Brighter colors indicate the location of more intense sources of gamma radiation.

“One of the first things that catches your eye in the film is a source moving in an arc across the screen. This is our Sun, whose apparent motion reflects its annual orbital motion around the Earth,” said Fermi Project Associate Scientist Judy Rakusin, who toured the film at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

In most cases, LAT perceives the Sun poorly due to the influence of accelerated particles (atomic nuclei moving at speeds close to the speed of light) called cosmic rays. When they collide with solar gas, or even the light it emits, gamma rays are produced. But sometimes the Sun suddenly shines with powerful explosions called solar flares, which can briefly make our star one of the brightest gamma-ray sources in the sky.

The film shows the sky from two different angles. The rectangular view shows the entire sky, with the center of our galaxy in the middle. This highlights the central plane of the Milky Way, glowing with gamma rays produced by cosmic rays striking interstellar gas and starlight. It is also filled with many other sources, including neutron stars and supernova remnants. Above and below this central band, we look out from our galaxy into a larger universe full of bright, rapidly changing sources.

Many of these are actually distant galaxies and are best viewed from a different perspective, focusing on the north and south poles of our galaxy. Each of these galaxies, called blazars, contains a central black hole with a mass of a million or more solar masses.

For some reason, black holes create extremely fast-moving jets of matter, and in blazars we are looking almost directly at one of these jets, an image that increases their brightness and variability. “The variations show us that something has changed in these planes,” Rakuzin said. “We observe these sources regularly and alert other telescopes in space and on the ground when something interesting happens. We have to be quick to catch these flares before they disappear, and the more observations we can collect, the better we can understand these events.”

Fermi plays a key role in a growing network of missions working together to capture these changes in the universe as they occur.

Most of these galaxies are very distant. For example, light from the blazar known as 4C +21.35 took 4.6 billion years to travel; This means that the explosion we see today actually occurred when the Sun and our Solar System began to form. Other bright blazars are more than twice as distant, and together they provide impressive snapshots of the black hole’s activity over cosmic time.

Many of the short-lived events studied by Fermi, such as gamma-ray bursts, the most powerful cosmic explosions, cannot be seen in slow motion. This is the result of several days of data processing to sharpen the images.

The Fermi Space Gamma-ray Telescope is a partnership in astrophysics and particle physics directed by Goddard. Fermi was developed in collaboration with the US Department of Energy with the participation of scientific institutions and partners from France, Germany, Italy, Japan, Sweden and the US.