In a cosmic game of galactic hide-and-seek, NASA's Hubble Space Telescope has captured a sweeping barred spiral galaxy that's roughly the size of our own Milky Way - but the real party trick is tucked into the lower-right corner. There, a distant background galaxy is being magnified and distorted by the gravity of a closer galaxy, a phenomenon known as gravitational lensing. It's like a funhouse mirror, except the mirror is spacetime and the funhouse is the entire universe.

This particular image is one of many gravitational lensing observations Hubble has taken in preparation for science with the new Nancy Grace Roman Space Telescope. Think of Hubble as the diligent intern doing the groundwork while Roman prepares to swoop in with its much larger field of view. Gravitational lensing occurs when the mass of a foreground object - such as a galaxy - warps spacetime, causing light to bend, distort, and magnify as it passes around the object, similar to a giant lens in space. This requires a precise chance alignment between the foreground and background galaxies, because the universe, apparently, has a sense of dramatic timing.

In this image, the gravitational lens features a foreground elliptical galaxy about 4.5 billion light-years away. That means the light we see from this galaxy now would have first started traveling toward us when our solar system was still forming - so, roughly, when Earth was still a molten hellscape and nobody had invented the wheel yet. The background galaxy is about eight billion light-years away, almost twice as far. It appears as a pair of arcs: one large and very noticeable to the upper left of the foreground galaxy, the other a much smaller, flipped image of the same background galaxy to the lower right. This configuration is called an arc-counterarc pair, which sounds like a fancy gymnastics move but is actually just gravity being its usual overachieving self.

The more massive the foreground galaxy is, the stronger the gravitational lens and the more significantly it bends light. By studying the distortion of the background galaxy, researchers can determine how much mass the foreground galaxy contains. This plays a huge role in the study of dark matter, the mysterious, invisible substance that makes up the majority of mass in the universe. The visible matter is not enough to account for the level of distortion in the background galaxy, which allows researchers to calculate both the mass of the foreground galaxy and how much dark matter it contains. In other words, the universe is mostly made of something we can't see, and we're using a giant cosmic magnifying glass to figure out how much of it is lurking in any given galaxy. Science!

Almost all of the objects in this image are galaxies, except for a few scattered foreground stars. The barred spiral galaxy in this image - so called because its arms extend from a bar of stars in its center - is about the size of our own Milky Way galaxy, which astronomers think is a barred spiral as well. The tiny spiral to the left of the large spiral may be a satellite galaxy, similar to the Large and Small Magellanic Clouds that orbit the Milky Way. It's like a galactic entourage.

Hubble views the cosmos primarily in visible and ultraviolet light with some infrared coverage, while Roman sees mainly infrared wavelengths and some visible light. Hubble can provide high-resolution views of individual objects, while Roman has a much larger field of view conducive to panoramas. So Hubble is the portrait photographer, and Roman is the landscape artist. Together, they'll build an even more comprehensive picture of the cosmos.

This is just one of many gravitational lens images captured by Hubble. Astronomers will use them to analyze gravitational distortions to learn more about dark matter in the foreground galaxies and to lay the groundwork for future Roman observations. Hubble can only view these gravitational lenses one at a time, while Roman's wide view of the sky will provide a greater sample of these lenses. Astronomers are using Hubble's sharp images to build a computer model to better analyze dark matter-induced distortions. This tool will help astronomers analyze Roman's large images. Hubble will also follow up on interesting lenses Roman detects, because even a new telescope needs a wingman.

Claire Andreoli of NASA's Goddard Space Flight Center in Greenbelt, MD, is credited with the release. No word on whether she also does birthday parties.