The Hubble Space Telescope in a picture snapped by a Servicing Mission 4 crewmember just after the Space Shuttle Atlantis captured Hubble with its robotic arm on May 13, 2009, beginning the mission to upgrade and repair the telescope.The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute conducts Hubble science operations.Goddard is responsible for HST project management, including mission and science operations, servicing missions, and all associated development activities.

The Hubble Space Telescope in a picture snapped by a Servicing Mission 4 crewmember just after the Space Shuttle Atlantis captured Hubble with its robotic arm on May 13, 2009, beginning the mission to upgrade and repair the telescope.The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute conducts Hubble science operations.Goddard is responsible for HST project management, including mission and science operations, servicing missions, and all associated development activities.

Photo by: NASA Goddard

NASA Goddard

How Astronomers Use a Trick of Gravity to See the Most Distant Objects in the Universe

Let’s say you’re an astronomer (work with me here) and you want to take a picture of something incredibly, deeply far away. You know, the typical business of astronomy.

August 18, 2022

You have at your disposal two tried-and-true methods to beef up your observing capacity. One is the size of your telescope. The bigger you make it, the more light it will collect. That makes it easier to catch faint, distant things.

Your other option is observation time. If you stare at a single point for hour after hour, you can collect all the light coming from that point. You add it all together using your fancy digital camera and there you have it: an image of a very deep object.

But what if you’ve maxed out both of those methods. What if you’re using the biggest possible telescope for the longest amount of time, and this is all the light you’re ever going to collect? Are you stuck here? Is this the ultimate limit of your observing capacity?

SPACE TELESCOPE-ARTIST'S CONCEPT-SIDE VIEW

SPACE TELESCOPE-ARTIST'S CONCEPT-SIDE VIEW

Photo by: Hubble Space Telescope

Hubble Space Telescope

If you were an astronomer before modern times, then yes. If you couldn’t see something, you simply couldn’t see something. And with ever larger telescopes, we’ve been able to push back into the distant reaches of the cosmos.

Almost.

Even with today’s technology, with telescopes in space and monster laser-guided observatories on the ground, we can’t see the most distant galaxies in the Universe. They’re simply too far away and too faint for us to directly image.

Thankfully, nature helps us out, but only if we’re lucky.

One of the most astounding aspects of Einstein’s general theory of relativity is that gravity can act like a lens. The presence of a massive object, like a planet or a star or a gigantic cluster of galaxies, bends and warps space around it. Beams of light are obligated to follow the curvature caused by those objects, and so those objects act exactly like lenses do: bending the path of light around them.

GALAXY NGC 3310 IS ONE OF SEVERAL STARBURST GALAXIES, WHICH ARE HOTBEDS OF STAR FORMATION BEING STUDIED BY DOCTOR MEURER, GERHARDT AND A TEAM OF SCIENTISTS AT JOHNS HOPKINS UNIVERSITY, LAUREL, MARYLAND.

GALAXY NGC 3310 IS ONE OF SEVERAL STARBURST GALAXIES, WHICH ARE HOTBEDS OF STAR FORMATION BEING STUDIED BY DOCTOR MEURER, GERHARDT AND A TEAM OF SCIENTISTS AT JOHNS HOPKINS UNIVERSITY, LAUREL, MARYLAND.

Photo by: Hubble Space Telescope

Hubble Space Telescope

If we look at a giant cluster of galaxies, which can easily weigh over a quadrillion times the mass of the sun, we’re looking at a giant gravitational lens. If there’s some object in the background (say, a random galaxy sitting far behind it), then the light coming from that background object has to pass around and through the intervening cluster.

We see this light get all kinds of crazy distorted, forming rings and loops and fun twisting shapes. To give yourself an idea of what this looks like, pick up your nearest wine glass and look through the stem – it turns out that the math of gravitational lensing causes light to behave in a very similar way.

All this bending of light also causes a magnification effect, as light from different directions gets concentrated into a single point. With this technique, astronomers can leap-frog past the galaxy cluster and get glimpses into the more distant universe. For example, astronomers have used this method recently to find the most distant star ever recorded.

We only get glimpses, however, as it relies on finding these lucky coincidences between galaxy clusters and background objects. But we’ll take what we can get…as we continue building even more powerful telescopes.

Paul M. Sutter

Paul M. Sutter is an astrophysicist at Stony Brook University and the Flatiron Institute, host of Ask a Spaceman and Space Radio, and author of How to Die in Space.

Next Up

Asteroid Ryugu Has Dust Grains Older Than the Sun. How?

In 2018 the Japanese space agency sent the Hayabusa2 mission to the asteroid Ryugu, As a part of that mission, the spacecraft blasted material off the surface of the asteroid, put it in a bottle, and sent it back to Earth. Two years later that sample landed in the western deserts of Australia.

Why We Know Nothing about Dark Matter and Dark Energy

Welcome to the era of precision cosmology…where we’ve managed to very precisely measure everything we don't know about the universe.

What Comes After the Moon and Mars?

Space hotels may be in our future.

Scientists in China Discover Rare Moon Crystal that Could Power Earth

A rare lunar crystal found on the near side of the moon is giving scientists hope of providing limitless power for the world – forever.

What Screaming Black Holes are Telling Us

In 2002, NASA’s orbiting X-ray observatory, the Chandra telescope, mapped out the movements of hot gas in a cluster of galaxies sitting 250 million light-years away.

When We’ll Know if NASA’s Asteroid Impact Test was a Success

Recently NASA’s DART mission succeeded in its primary goal, which was to slam a spacecraft face-first into an asteroid. For science. The intention of the mission was to test if we could actually redirect an asteroid and send it into a different orbit. But how and when will we know if it worked?

Quiz: Test Your Space Exploration Knowledge

Ahead of the historic May 27th NASA and SpaceX crewed space launch, test your space exploration knowledge!

How to Save Humanity from Extinction

Here are some goals we need to achieve if we want to reach our 500,000th birthday as a species.

What We’ve Already Learned From James Webb? (Hint: it’s a lot)

That was worth the wait. Just a quick handful of months since its historic launch on Christmas Day, the James Webb Space Telescope has flown to its observing position, unfolded its delicate instruments and ultra-sized mirror, and run through a suite of checks and alignments and calibrations. The team at NASA behind the telescopes released their first batch of images from the science runs, and besides being gorgeous, they're powerful.

Why Astronomers Care About Super-Old Galaxies?

A long time ago, our universe was dark.It was just 380,000 years after the big bang. Up until that age, our entire observable cosmos was less than a millionth of its present size. All the material in the universe was compressed into that tiny volume, forcing it to heat up and become a plasma. But as the universe expanded and cooled, eventually the plasma changed into a neutral gas as the first atoms formed.

Related To: