Physics Meme

Hubble’s Guide to Viewing Deep Fields

They say a picture is worth a thousand words, but no images have left a greater impact on our understanding of the universe quite like the Hubble Space Telescope’s deep fields. Like time machines, these iconic images transport humanity billions of light-years back in time, offering a glimpse into the early universe and insight into galaxy evolution!

You’ve probably seen these images before, but what exactly do we see within them? Deep field images are basically core samples of our universe. By peering into a small portion of the night sky, we embark on a journey through space and time as thousands of galaxies appear before our very eyes.

So, how can a telescope the size of a school bus orbiting 340 miles above Earth uncover these mind-boggling galactic masterpieces? We’re here to break it down. Here’s Hubble’s step-by-step guide to viewing deep fields:

Step 1: Aim at the darkness

Believe it or not, capturing the light of a thousand galaxies actually begins in the dark. To observe extremely faint galaxies in the farthest corners of the cosmos, we need minimal light interference from nearby stars and other celestial objects. The key is to point Hubble’s camera at a dark patch of sky, away from the outer-edge glow of our own galaxy and removed from the path of our planet, the Sun, or the Moon. This “empty” black canvas of space will eventually transform into a stunning cosmic mosaic of galaxies.

The first deep field image was captured in 1995. In order to see far beyond nearby galaxies, Hubble’s camera focused on a relatively empty patch of sky within the constellation Ursa Major. The results were this step-shaped image, an extraordinary display of nearly 3,000 galaxies spread across billions of light-years, featuring some of the earliest galaxies to emerge shortly after the big bang.

Step 2: Take it all in

The universe is vast, and peering back billions of years takes time. Compared to Hubble’s typical exposure time of a few hours, deep fields can require hundreds of hours of exposure over several days. Patience is key. Capturing and combining several separate exposures allows astronomers to assemble a comprehensive core slice of our universe, providing key information about galaxy formation and evolution. Plus, by combining exposures from different wavelengths of light, astronomers are able to better understand galaxy distances, ages, and compositions.

The Hubble Ultra Deep Field is the deepest visible-light portrait of our universe. This astonishing display of nearly 10,000 galaxies was imaged over the course of 400 Hubble orbits around Earth, with a total of 800 exposures captured over 11.3 days.

Step 3: Go beyond what’s visible

The ability to see across billions of light-years and observe the farthest known galaxies in our universe requires access to wavelengths beyond those visible to the human eye. The universe is expanding and light from distant galaxies is stretched far across space, taking a long time to reach us here on Earth. This  phenomenon, known as “redshift,” causes longer wavelengths of light to appear redder the farther they have to travel through space. Far enough away, and the wavelengths will be stretched into infrared light. This is where Hubble’s infrared vision comes in handy. Infrared light allows us to observe light from some of the earliest galaxies in our universe and better understand the history of galaxy formation over time.

In 2009, Hubble observed the Ultra Deep Field in the infrared. Using the Near Infrared Camera and Multi-Object Spectrometer, astronomers gathered one of the deepest core samples of our universe and captured some of the most distant galaxies ever observed.

Step 4: Use your time machine

Apart from their remarkable beauty and impressive imagery, deep field images are packed with information, offering astronomers a cosmic history lesson billions of years back in time within a single portrait. Since light from distant galaxies takes time to reach us, these images allow astronomers to travel through time and observe these galaxies as they appear at various stages in their development. By observing Hubble’s deep field images, we can begin to discover the questions we’ve yet to ask about our universe.

Credit: NASA, ESA, R. Bouwens and G. Illingworth (University of California, Santa Cruz)

Hubble’s deep field images observe galaxies that emerged as far back as the big bang. This image of the Hubble Ultra Deep Field showcases 28 of over 500 early galaxies from when the universe was less than one billion years old. The light from these galaxies represent different stages in their evolution as their light travels through space to reach us.

Step 5: Expand the cosmic frontier

Hubble’s deep fields have opened a window to a small portion of our vast universe, and future space missions will take this deep field legacy even further. With advancements in technologies and scientific instruments, we will soon have the ability to further uncover the unimaginable.

Slated for launch in late 2021, NASA’s James Webb Space Telescope will offer a new lens to our universe with its impressive infrared capabilities. Relying largely on the telescope’s mid-infrared instrument, Webb will further study portions of the Hubble deep field images in greater detail, pushing the boundaries of the cosmic frontier even further.

And there you have it, Hubble’s guide to unlocking the secrets of the cosmos! To this day, deep field images remain fundamental building blocks for studying galaxy formation and deepening not only our understanding of the universe, but our place within it as well.

Still curious about Hubble Deep Fields? Explore more and follow along on Twitter, Facebook, and Instagram with #DeepFieldWeek!

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Would anybody like me to do a lesson on the Three Laws of Thermodynamics???

why are cheetahs not technically big cats? is it just because they're weird as hell or do they not meet some big cat criteria?

so the thing about Big Cats is that they’re all closely related members of the genus Panthera! 

because they’re all part of the same lineage, they share a lot of traits like the ability to roar.

and cheetahs are actually members of a completely different cat lineage altogether, the genus Acinonyx!

they’re not very closely related to the big cats at all and are actually most closely related to Pumas, which you can totally see if you stack them up next to each other and squint really hard. 

it’s okay though, the cheetah can still be the biggest cat in our hearts :’)

"I do not know how I may appear to the world, but to myself I seem to have been only like a boy, playing on the sea-shore, and diverting myself, in now and then finding a smoother pebble or prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me."

-Isaac Newton-

hey everyone! i’m a peer tutor at my university and i wanted to share some study strategies that i’ve found really helpful in my stem/content-heavy courses. please feel free to share yours with me as well!

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Keep reading

Weird and Wonderful Irregular Galaxies

Spiral and elliptical galaxies seem neatly put together, but what happened to irregular galaxies? Irregular galaxies have one-of-a-kind shapes and many look like blobs! Why do they look the way they do? Astronomers think the uniqueness of these galaxies results from their interactions with other galaxies — like when they pass close to one another or even collide!

Looking back at the early universe with the help of our Hubble Space Telescope’s “deep field” observations, astronomers can peek at galaxies millions and billions of light-years away. They noticed that these far-away galaxies appear unusually messy, showing more star formation and mergers than galaxies closer to the Milky Way.

We also see irregular galaxies closer to home, though. Some may form when two galaxies pass close together in a near-miss. When this happens, their gravity pulls stars out of place in both galaxies, messing up the neat structure they originally had as spiral or elliptical galaxies. Think of it like this: you happen to have a pile of papers sitting at the edge of a table and when someone passes close by the papers become ruffled and may scatter everywhere! Even though the two galaxies never touched, gravity's effects leave them looking smeared or distorted.

Some irregular galaxies result from the collision between two galaxies. And while some of these look like a blob of stars and dust, others form dazzling ring galaxies! Scientists think these may be a product of collisions between small and large galaxies. These collisions cause ripples that disturb both galaxies, throwing dust, gas, and stars outward. When this happens, it pushes out a ring of material, causing gas clouds to collide and spark the birth of new stars. After just a few million years, stars larger than our Sun explode as supernovae, leaving neutron stars and black holes throughout the ring!

Not all galaxy collisions create irregular galaxies — our Milky Way spiral galaxy has gone through many mergers but has stayed intact! And for some interacting galaxies, being an irregular galaxy may just be a phase in their transformation. We’re observing them at a snapshot in time where things are messy, but they may eventually become neat and structured spirals and ellipticals.

Irregular galaxies are similar to each other, but unique and beautiful because of their different interactions, whether they’re just passing another galaxy or taking part in a dramatic collision. Keep up with NASA Universe on Facebook and Twitter where we post regularly about galaxies.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

Roman’s Heat-Vision Eyes Are Complete!

Our Nancy Grace Roman Space Telescope team recently flight-certified all 24 of the detectors the mission needs. When Roman launches in the mid-2020s, the detectors will convert starlight into electrical signals, which will then be decoded into 300-megapixel images of huge patches of the sky. These images will help astronomers explore all kinds of things, from rogue planets and black holes to dark matter and dark energy.

Eighteen of the detectors will be used in Roman’s camera, while another six will be reserved as backups. Each detector has 16 million tiny pixels, so Roman’s images will be super sharp, like Hubble’s.

The image above shows one of Roman’s detectors compared to an entire cell phone camera, which looks tiny by comparison. The best modern cell phone cameras can provide around 12-megapixel images. Since Roman will have 18 detectors that have 16 million pixels each, the mission will capture 300-megapixel panoramas of space.

The combination of such crisp resolution and Roman’s huge view has never been possible on a space-based telescope before and will make the Nancy Grace Roman Space Telescope a powerful tool in the future.

Learn more about the Roman Space Telescope!

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That's a wrap! Thank you all for the wonderful questions.

NASA Mars Perseverance Rover Mission Engineer Chloe Sackier answered questions about how we prepared for the mission, Perseverance’s entry, descent, and landing, and what Perseverance will do once on Mars.

Check out her full Answer Time for more: Career | Preparation | Entry, Descent, & Landing | Operation

We hope you had fun today and learned a little bit about our robotic astrobiologist landing on Mars on February 18th. You won't want to miss this! Tune in to NASA TV HERE starting at 2:15 p.m. EST.

If today’s Answer Time got you excited, team up with us to #CoutdownToMars! We created a virtual Mars photo booth, have sounds of Mars to listen to and more for all you Earthlings to channel your inner Martian. Check out ways to participate HERE.

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com