The Hubble Space Telescope’s Still Got It

NGC 1566
ESA/Hubble & NASA, D. Calzetti and the LEGUS team, R. Chandar

NASA’s Hubble Space Telescope is often overshadowed by the shiny new observatory in the room, the James Webb Space Telescope, but its latest photo of a gorgeous spiral galaxy is a nice reminder that ol’ reliable can still impress.

The Hubble Space Telescope has been in orbit around Earth for 33 years — that’s more than twice the amount of time that scientists intended the observatory to be in operation. In 2020, NASA celebrated the telescope’s 30th anniversary with 30 newly-processed images captured by Hubble that featured galaxies, star clusters, and nebulae.

That massive drop of photos serves to highlight the importance of Hubble to space observations, as it is still used regularly alongside the newer James Webb Space Telescope by astronomers the world over. Hubble has managed to stay in working order for so long thanks mainly to multiple in-person servicing missions to the observatory that upgraded and improved it. However, those missions ceased after the final servicing mission in 2009 with the retirement of the space shuttle program.

Hubble experienced a couple of scary close-calls in 2021 — one which caused its Wide Field Camera 3 (its most used camera) to go offline — that could have seen the end of the storied observatory, but NASA was able to address both situations remotely and the satellite has been in full working order since.

All of this is why it’s important to feature and appreciate Hubble’s continued work. Today, NASA published its latest photo of sprial galaxy NGC 1566, above, which is known as a “weakly barred” or intermediate spiral galaxy. It is called this because it does not have a clearly present or clearly absent bar-shaped structure at its center, the European Space Agency (ESA) explains.

It is nicknamed the “Spanish Dancer Galaxy” because of its vivid and dramatic swirling spiral arms that evoke the idea of a dancer’s moving form. NGC 1566 sits around 60 million light-years from Earth in the constellation Dorado and is part of the Dorado galaxy group.

“A galaxy group is a collection of gravitationally bound galaxies. They differ from galaxy clusters in size and mass: galaxy clusters may hold hundreds of galaxies, while galaxy groups might only hold several tens of galaxies. However, groups are the most common collection of galaxies in the universe, holding more than 50% of all galaxies. Although there is currently no precise number delineation between the definition of a galaxy group and a galaxy cluster, some astronomers have suggested that collections with less than 80 trillion Suns should be classified as galaxy groups,” the ESA says.

“The Dorado group membership has fluctuated over the past few decades, as various scientific papers changed its list of constituent galaxies. This is one example of why it is so challenging for astronomers to pin down members of galaxy groups like the Dorado group. One way to better understand this problem is by imagining a photograph of an adult human and a large oak tree. We know the approximate size of the person and the tree, so if we see a photo where the person appears roughly the same size as the tree, then we would assume that, in reality, the person was much closer to the camera than the tree. When astronomers try to figure out which galaxies are members of a galaxy group, they do not necessarily know the size of the individual galaxies. Instead, they have to work out whether the galaxies really are relatively close together in space, or whether some of them are actually much closer or much further away. This process is easier with more sophisticated observation techniques, but it still can present a challenge.”

A full resolution TIFF of Hubble’s photo can be downloaded from the ESA’s website.