Stunning image captures two overlapping galaxies

What could be more beautiful than one shiny spiral galaxy? Two. A new image of a “galactic overlap” from the NASA/ESA Hubble Space Telescope and the Galaxy Zoo citizen science project appears to show two dueling galaxies more than a billion light-years away from Earth. For a closer look, there is a zoomable version of the image.

While the galaxies SDSS J115331 and LEDA 2073461 may appear to collide, they just align by chance and ESA compared them to two ships passing at night. Hubble has recorded similar galaxies that appear to be related in the past, such as NGC 1512 and NGC 1510 in 2017 and NGC 6285 and NGC 6286 in 2019.

Two overlapping spiral galaxies (SDSS J115331 and LEDA 2073461) orbit nearly a billion light-years from Earth. CREDIT: ESA/Hubble & NASA, W. Keel. ESA/Hubble & NASA, W. Keel

[Related: Hubble image captures stars forming in a far-off phantom galaxy.]

This is one of many Hubble galaxy observations in which the Galaxy Zoo project has played a major role. Since 2007, the citizen science project and its successors, including Galaxy Zoo 2 and Galaxy Zoo: CANDELS, have collected galaxy classifications from nearly 90,000 volunteer astronomers. The citizen scientists classify galaxies imaged by robotic telescopes and are often the first to ever see an astronomical object, according to the European Space Agency (ESA). To date, Galaxy Zoo has classified 5,134,932 galaxies. Galaxy Zoo volunteers have also discovered a “menagerie of strange and wonderful galaxies,” such as unusual three-armed spirals and colliding ring galaxies.

From our perspective on Earth, it’s not uncommon for galaxies to overlap in this way. In July, the new NASA/ESA/CSA James Webb Space Telescope (JWST) captured a 150-million-pixel image of a group of five galaxies that appear to be swirling together, called Stephan’s Quintet. In this group of five, only a few galaxies in the group interact. According to NASA, images like these “provide new insights into how galactic interactions fueled the evolution of galaxies in the early universe.”

[Related: Behold six galactic collisions, masterfully captured by Hubble.]

Galaxies are classified into three main categories: elliptical, spiral and irregular. Ellipticals make up about a third of all galaxies and can range from nearly circular to more elongated. The largest and rarest are called giant elliptical bodies and are about 300,000 light-years across.

Spiral galaxies are very colorful. They usually appear as flat, blue-white disks of stars, gas, and dust with yellow-looking bulges in the center. There are two types of spiral galaxies, normal and barred. Striped spirals have a bar of stars running through the central bulge, and the arms usually start at the end of the bar instead of a bulge. Normal spirals have arms extending from a center, which look like a hurricane’s eye.

Irregular galaxies are (as the name suggests) the most unusual galaxy. They are not disk-like or elliptical and contain very little dust. These are often seen by astronomers as they gaze deeper into the universe. Looking that deep is like looking back in time, and irregular galaxies abound in the early Universe, before spirals and ellipticals even evolved.