Hubble charts gravitational lenses for Roman

NASA’s announcement published Thursday 22 October 2026 said NASA’s Hubble Space Telescope has captured gravitational lensing images in preparation for science with the Nancy Grace Roman Space Telescope.

In one image, a foreground elliptical galaxy about 4.5 billion light-years away acts as a gravitational lens. Its gravity magnifies and distorts light from a background galaxy about eight billion light-years away, which appears as a large arc and a smaller, flipped image.

The announcement said gravitational lensing occurs when the mass of a foreground object warps spacetime and bends light passing around it. The background galaxy appears as an arc-counterarc pair because of the chance alignment between the foreground and background galaxies.

Researchers can study the distortion to determine how much mass the foreground galaxy contains. NASA said visible matter does not account for the level of distortion, allowing researchers to calculate the galaxy’s mass and the amount of dark matter it contains.

Hubble captures gravitational lens images in visible and ultraviolet light, with some infrared coverage. Roman sees mainly infrared wavelengths and some visible light. Hubble provides high-resolution views of individual objects, while Roman has a much larger field of view for panoramas.

NASA said astronomers are using Hubble images to build a computer model for analyzing dark matter-induced distortions. The model will help analyze Roman’s large images. Hubble can view gravitational lenses one at a time, while Roman’s wide view will provide a greater sample. Hubble will also follow up on lenses Roman detects.