Why astronomers keep staring at the same spot in the sky

The universe is enormous, yet astronomers have looked at a few parts of the night sky again and again. Lots of telescopes – from the Hubble Space Telescope Unpleasant JWST and beyond – looked at the Magellanic Cloudstwo mini-galaxies in our celestial neighborhood, right around the Milky Way. But why do scientists look at the same thing so often, when there is so much universe to choose from?

It turns out that having a lot of information about one example of a celestial phenomenon actually helps astronomers understand the whole picture a lot better, leading to important scientific advances. The Magellanic Clouds in particular are an excellent laboratory for studying how galaxies interact with each other – gas and dust swirling between them, changing their shapes and even exchanging entire stars – as well as how stars form.

The two Magellanic Clouds are known as the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC), and they are located right in our cosmic backyard. They are just over 150,000 light years away, which seems far until you notice the distant edges of the Milky Way itself extend over 300,000 light years. Meanwhile, our nearest large neighboring galaxy, Andromedais no less than 2.6 million light years away.

The LMC and SMC are literally intertwined with each other and with the Milky Way. The so-called Magellanic Current is a string of gas that moves between the LMC and our own galaxy, and the Magellanic Bridge is a similar structure between the LMC and SMC. These rivers of stars and other material are evidence of the action of gravity, which siphons material from dwarf galaxies when they get too close to our colossal galaxy.

As gravity moves around stellar material, new stars are born from clouds of gas and dust. The LMC and SMC are particularly active hubs of star formation and offer scientists a chance to get up close and personal with them how the raw materials for stars circulate in a galaxy. For example, images of the Spitzer Space Telescopewho observed with infrared thermal vision, revealed where new star formation is consuming dust in the GMC and where it spits out its leftovers.

Since astronomers can’t make a star in a lab and perform neatly controlled experiments, they must instead look at things in space from as many perspectives as possible. Imagine having to understand what a sculpture is made of and how it was carved, but you can’t touch it and you can only look at it from across the room. You’ll have to be creative with how you learn about it. take photos from different angles.

In astronomy, the different ‘angles’ of photographs are actually observations in different wavelengths of light. By looking at something across the entire electromagnetic spectrum, astronomers gather more information (several pieces of the very distant puzzle) about whatever space object they are looking at. For example, infrared observations with JWST showed how dusty star formation in the nearby LMC is different from that of galaxies from the universe’s infancy, while Chandra x-ray observations spotted signs of energetic young stars in the clouds.

There are also a whole host of tricks astronomers play with light to extract even more information without directly interacting with a distant galaxy. Spectroscopyfor example, splits light into all its different wavelengths, allowing astronomers to see what type of light is coming from an object and thus determine what it is made of; in the Magellanic Clouds (and beyond) this is how astronomers figure out which elements are in a star. Another technique, polarimetrysplits light into two polarization states (a bit like beautiful, polarizing sunglasses that block some of Earth’s bright blue sky light). Astronomers used polarimetry to spy bright baby stars as they illuminated their surroundings in the Magellanic Clouds.

Furthermore, if astronomers continue to view the same object with their telescopes, they can see how that object changes over time. Even though galaxies and stars live on much longer time scales than humans, interesting differences can still often be seen over the course of just a few years. The passage of time also has the added benefit of making our technology on Earth get better and better: telescopes today can see in much more detail than they could twenty years ago.

Astronomers know this is part of the process; A a recent project that revisited the Magellanic Clouds was even cleverly named “Yes, Magellanic Clouds Again.” That new look at the same old target revealed some stars that were unexpectedly old, plus some new structures that scientists hadn’t noticed before. Even though the Magellanic Clouds have been photographed with all our best telescopes so far, they will certainly be the focus of a new campaign in the future. We will always have more to learn, more details to understand and refine when it comes to the mysteries of space.