Even though black holes swallow anything that comes near them — even light — they are still possible to locate by looking for signs of their effects. Black holes are extremely dense, so they have a lot of mass and a strong gravitational effect that can be observed from light-years away. But the universe is a big place, and researchers are hoping that the public can help them to identify more black holes in the name of scientific exploration.

A project called Black Hole Hunter invites members of the public to search through data collected by NASA’s Transiting Exoplanet Survey Satellite (TESS) to look for signs of a black hole. Using a technique called gravitational microlensing, citizen scientists will look at how the brightness of light from various stars changes over time, looking for indications that a black hole could have passed in front of a star and bent the light coming from it. This should enable the project to identify black holes that would otherwise be invisible.

One of the researchers on the project, Matt Middleton of the University of Southampton, explained in a statement: Black holes are invisible. Their gravitational pull is so strong that not even light can escape, making them incredibly hard to see, even with specialist equipment. But that gravitational pull is also how we can detect them because it’s so strong that it can bend and focus light, acting like a lens that magnifies light from stars. We can detect this magnification and that’s how we know a black hole exists.

This week’s image from the Hubble Space Telescope shows the aftermath of an epic explosion in space caused by the death of a massive star.

Some of the most dramatic events in the cosmos are supernovas, when a massive star runs out of fuel to fuse — first running out of hydrogen, then helium, then burning through heavier elements — and eventually can no longer sustain the outward pressure from heat caused by this fusion. When that happens, the star collapses suddenly into a dense core, and its outer layers are thrown off in a tremendous explosion called a Type II supernova.

The space between streams of stars may be influenced by the presence of the universe’s most mysterious form of matter.

Perhaps the greatest and most frustrating mystery in cosmology is the Hubble tension problem. Put simply, all the observational evidence we have points to a universe that began in a hot, dense state, and then expanded at an ever-increasing rate to become the universe we see today. Every measurement of that expansion agrees with this, but where they don’t agree is on what that rate exactly is.

We can measure expansion in lots of different ways, and while they are in the same general ballpark, their uncertainties are so small now that they don’t overlap. There is no value for the Hubble parameter that falls within the uncertainty of all measurements, hence the problem.

Of course, most of the results depend on a long chain of observational results. When we measure cosmic expansion using distant supernovae, for example, the result depends on the derived distances of these supernovae as found through the cosmic distance ladder, where ever greater distances are determined based on the distance of closer things.

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Astronomers spot periodic lights coming from near the black hole at the center of our galaxy.

The supermassive structure dates to about 400 million years after the Big Bang, and it’s particularly large for its age.