Spitzer - Blog Posts

Astronomers used three of NASA's Great Observatories to capture this multiwavelength image showing galaxy cluster IDCS J1426.5+3508. It includes X-rays recorded by the Chandra X-ray Observatory in blue, visible light observed by the Hubble Space Telescope in green, and infrared light from the Spitzer Space Telescope in red. This rare galaxy cluster has important implications for understanding how these megastructures formed and evolved early in the universe.

How Astronomers Time Travel

Let’s add another item to your travel bucket list: the early universe! You don’t need the type of time machine you see in sci-fi movies, and you don’t have to worry about getting trapped in the past. You don’t even need to leave the comfort of your home! All you need is a powerful space-based telescope.

But let’s start small and work our way up to the farthest reaches of space. We’ll explain how it all works along the way.

This animation illustrates how fast light travels between Earth and the Moon. The farther light has to travel, the more noticeable its speed limit becomes.

The speed of light is superfast, but it isn’t infinite. It travels at about 186,000 miles (300 million meters) per second. That means that it takes time for the light from any object to reach our eyes. The farther it is, the more time it takes.

You can see nearby things basically in real time because the light travel time isn’t long enough to make a difference. Even if an object is 100 miles (161 kilometers) away, it takes just 0.0005 seconds for light to travel that far. But on astronomical scales, the effects become noticeable.

This infographic shows how long it takes light to travel to different planets in our solar system.

Within our solar system, light’s speed limit means it can take a while to communicate back and forth between spacecraft and ground stations on Earth. We see the Moon, Sun, and planets as they were slightly in the past, but it's not usually far enough back to be scientifically interesting.

As we peer farther out into our galaxy, we use light-years to talk about distances. Smaller units like miles or kilometers would be too overwhelming and we’d lose a sense of their meaning. One light-year – the distance light travels in a year – is nearly 6 trillion miles (9.5 trillion kilometers). And that’s just a tiny baby step into the cosmos.

The Sun’s closest neighboring star, Proxima Centauri, is 4.2 light-years away. That means we see it as it was about four years ago. Betelgeuse, a more distant (and more volatile) stellar neighbor, is around 700 light-years away. Because of light’s lag time, astronomers don’t know for sure whether this supergiant star is still there! It may have already blasted itself apart in a supernova explosion – but it probably has another 10,000 years or more to go.

What looks much like craggy mountains on a moonlit evening is actually the edge of a nearby, young, star-forming region NGC 3324 in the Carina Nebula. Captured in infrared light by the Near-Infrared Camera (NIRCam) on NASA’s James Webb Space Telescope, this image reveals previously obscured areas of star birth.

The Carina Nebula clocks in at 7,500 light-years away, which means the light we receive from it today began its journey about 3,000 years before the pyramids of Giza in Egypt were built! Many new stars there have undoubtedly been born by now, but their light may not reach Earth for thousands of years.

An artist’s concept of our Milky Way galaxy, with rough locations for the Sun and Carina nebula marked.

If we zoom way out, you can see that 7,500 light-years away is still pretty much within our neighborhood. Let’s look further back in time…

This stunning image by the NASA/ESA Hubble Space Telescope features the spiral galaxy NGC 5643. Looking this good isn’t easy; 30 different exposures, for a total of nine hours of observation time, together with Hubble’s high resolution and clarity, were needed to produce an image of such exquisite detail and beauty.

Peering outside our Milky Way galaxy transports us much further into the past. The Andromeda galaxy, our nearest large galactic neighbor, is about 2.5 million light-years away. And that’s still pretty close, as far as the universe goes. The image above shows the spiral galaxy NGC 5643, which is about 60 million light-years away! That means we see it as it was about 60 million years ago.

As telescopes look deeper into the universe, they capture snapshots in time from different cosmic eras. Astronomers can stitch those snapshots together to unravel things like galaxy evolution. The closest ones are more mature; we see them nearly as they truly are in the present day because their light doesn’t have to travel as far to reach us. We can’t rewind those galaxies (or our own), but we can get clues about how they likely developed. Looking at galaxies that are farther and farther away means seeing these star cities in ever earlier stages of development.

The farthest galaxies we can see are both old and young. They’re billions of years old now, and the light we receive from them is ancient since it took so long to traverse the cosmos. But since their light was emitted when the galaxies were young, it gives us a view of their infancy.

This animation is an artist’s concept of the big bang, with representations of the early universe and its expansion.

Comparing how fast objects at different distances are moving away opened up the biggest mystery in modern astronomy: cosmic acceleration. The universe was already expanding as a result of the big bang, but astronomers expected it to slow down over time. Instead, it’s speeding up!

The universe’s expansion makes it tricky to talk about the distances of the farthest objects. We often use lookback time, which is the amount of time it took for an object’s light to reach us. That’s simpler than using a literal distance, because an object that was 10 billion light-years away when it emitted the light we received from it would actually be more than 16 billion light-years away right now, due to the expansion of space. We can even see objects that are presently over 30 billion light-years from Earth, even though the universe is only about 14 billion years old.

This James Webb Space Telescope image shines with the light from galaxies that are more than 13.4 billion years old, dating back to less than 400 million years after the big bang.

Our James Webb Space Telescope has helped us time travel back more than 13.4 billion years, to when the universe was less than 400 million years old. When our Nancy Grace Roman Space Telescope launches in a few years, astronomers will pair its vast view of space with Webb’s zooming capabilities to study the early universe in better ways than ever before. And don’t worry – these telescopes will make plenty of pit stops along the way at other exciting cosmic destinations across space and time.

Learn more about the exciting science Roman will investigate on X and Facebook.

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Celebrating Spitzer, One of NASA’s Great Observatories

As the Spitzer Space Telescope’s 16-year mission ends, we’re celebrating the legacy of our infrared explorer. It was one of four Great Observatories – powerful telescopes also including Hubble, Chandra and Compton – designed to observe the cosmos in different parts of the electromagnetic spectrum.

Light our eyes can see

The part of the spectrum we can see is called, predictably, visible light. But that’s just a small segment of all the wavelengths of the spectrum. The Hubble Space Telescope observes primarily in the visible spectrum. Our Chandra X-ray Observatory is designed to detect (you guessed it) X-ray emissions from very hot regions of the universe, like exploded stars and matter around black holes. Our Compton Gamma Ray Observatory, retired in 2000, produced the first all-sky survey in gamma rays, the most energetic and penetrating form of light.

Then there’s infrared…

Infrared radiation, or infrared light, is another type of energy that we can't see but can feel as heat. All objects in the universe emit some level of infrared radiation, whether they're hot or cold. Spitzer used its infrared instrument to make discoveries in our solar system (including Saturn's largest ring) all the way to the edge of the universe. From stars being born to planets beyond our solar system (like the seven Earth-size exoplanets around the star TRAPPIST-1), Spitzer's science discoveries will continue to inspire the world for years to come.

Multiple wavelengths

Together, the work of the Great Observatories gave us a more complete view and understanding of our universe.

Hubble and Chandra will continue exploring our universe, and next year they’ll be joined by an even more powerful observatory … the James Webb Space Telescope!

Many of Spitzer's breakthroughs will be studied more precisely with the Webb Space Telescope. Like Spitzer, Webb is specialized for infrared light. But with its giant gold-coated beryllium mirror and nine new technologies, Webb is about 1,000 times more powerful. The forthcoming telescope will be able to push Spitzer's science findings to new frontiers, from identifying chemicals in exoplanet atmospheres to locating some of the first galaxies to form after the Big Bang.

We can’t wait for another explorer to join our space telescope superteam!

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No, this red beam in space isn't a light saber! It's a galaxy, far, far away — 44 million light-years away, to be exact. 

We often imagine galaxies as having massive spiral arms or thick disks of dust, but not all galaxies are oriented face-on as viewed from Earth. From our viewpoint, our Spitzer Space Telescope can detect this galaxy's infrared light but can only view the entire galaxy on its side where we can't see its spiral features. We know it has a diameter of roughly 60,000 light-years — a little more than half the diameter of our own Milky Way galaxy.

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Solar System 10 Things: Spitzer Space Telescope

Our Spitzer Space Telescope is celebrating 15 years since its launch on August 25, 2003. This remarkable spacecraft has made discoveries its designers never even imagined, including some of the seven Earth-size planets of TRAPPIST-1. Here are some key facts about Spitzer:

1. Spitzer is one of our Great Observatories.

Our Great Observatory Program aimed to explore the universe with four large space telescopes, each specialized in viewing the universe in different wavelengths of light. The other Great Observatories are our Hubble Space Telescope, Chandra X-Ray Observatory, and Compton Gamma-Ray Observatory. By combining data from different kinds of telescopes, scientists can paint a fuller picture of our universe.

2. Spitzer operates in infrared light.

Infrared wavelengths of light, which primarily come from heat radiation, are too long to be seen with human eyes, but are important for exploring space — especially when it comes to getting information about something extremely far away. From turbulent clouds where stars are born to small asteroids close to Earth’s orbit, a wide range of phenomena can be studied in infrared light. Objects too faint or distant for optical telescopes to detect, hidden by dense clouds of space dust, can often be seen with Spitzer. In this way, Spitzer acts as an extension of human vision to explore the universe, near and far.

What’s more, Spitzer doesn’t have to contend with Earth’s atmosphere, daily temperature variations or day-night cycles, unlike ground-based telescopes. With a mirror less than 1 meter in diameter, Spitzer in space is more sensitive than even a 10-meter-diameter telescope on Earth.

3. Spitzer was the first spacecraft to fly in an Earth-trailing orbit.

Rather than circling Earth, as Hubble does, Spitzer orbits the Sun on almost the same path as Earth. But Spitzer moves slower than Earth, so the spacecraft drifts farther away from our planet each year.

This “Earth-trailing orbit” has many advantages. Being farther from Earth than a satellite, it receives less heat from our planet and enjoys a naturally cooler environment. Spitzer also benefits from a wider view of the sky by orbiting the Sun. While its field of view changes throughout the year, at any given time it can see about one-third of the sky. Our Kepler space telescope, famous for finding thousands of exoplanets – planets outside our solar system -- also settled in an Earth-trailing orbit six years after Spitzer.

4. Spitzer began in a “cold mission.”

Spitzer has far outlived its initial requirement of 2.5 years. The Spitzer team calls the first 5.5 years “the cold mission” because the spacecraft’s instruments were deliberately cooled down during that time. Liquid helium coolant kept Spitzer’s instruments just a few degrees above absolute zero (which is minus 459 degrees Fahrenheit, or minus 273 degrees Celsius) in this first part of the mission.

5. The “warm mission” was still pretty cold.

Spitzer entered what was called the “warm mission” when the 360 liters of liquid helium coolant that was chilling its instruments ran out in May 2009.

At the “warm” temperature of minus 405 Fahrenheit, two of Spitzer's instruments -- the Infrared Spectrograph (IRS) and Multiband Imaging Photometer (MIPS) -- stopped working. But two of the four detector arrays in the Infrared Array Camera (IRAC) persisted. These “channels” of the camera have driven Spitzer’s explorations since then.

6. Spitzer wasn’t designed to study exoplanets, but made huge strides in this area.

Exoplanet science was in its infancy in 2003 when Spitzer launched, so the mission’s first scientists and engineers had no idea it could observe planets beyond our solar system. But the telescope’s accurate star-targeting system and the ability to control unwanted changes in temperature have made it a useful tool for studying exoplanets. During the Spitzer mission, engineers have learned how to control the spacecraft’s pointing more precisely to find and characterize exoplanets, too.

Using what’s called the “transit method,” Spitzer can stare at a star and detect periodic dips in brightness that happen when a planet crosses a star’s face. In one of its most remarkable achievements, Spitzer discovered three of the TRAPPIST-1 planets and confirmed that the system has seven Earth-sized planets orbiting an ultra-cool dwarf star. Spitzer data also helped scientists determine that all seven planets are rocky, and made these the best-understood exoplanets to date.

Spitzer can also use a technique called microlensing to find planets closer to the center of our galaxy. When a star passes in front of another star, the gravity of the first star can act as a lens, making the light from the more distant star appear brighter. Scientists are using microlensing to look for a blip in that brightening, which could mean that the foreground star has a planet orbiting it. Microlensing could not have been done early in the mission when Spitzer was closer to Earth, but now that the spacecraft is farther away, it has a better chance of measuring these events.

7. Spitzer is a window into the distant past.

The spacecraft has observed and helped discover some of the most distant objects in the universe, helping scientists understand where we came from. Originally, Spitzer’s camera designers had hoped the spacecraft would detect galaxies about 12 billion light-years away. In fact, Spitzer has surpassed that, and can see even farther back in time – almost to the beginning of the universe. In collaboration with Hubble, Spitzer helped characterize the galaxy GN-z11 about 13.4 billion light-years away, whose light has been traveling since 400 million years after the big bang. It is the farthest galaxy known.

8. Spitzer discovered Saturn’s largest ring.

Everyone knows Saturn has distinctive rings, but did you know its largest ring was only discovered in 2009, thanks to Spitzer? Because this outer ring doesn’t reflect much visible light, Earth-based telescopes would have a hard time seeing it. But Spitzer saw the infrared glow from the cool dust in the ring. It begins 3.7 million miles (6 million kilometers) from Saturn and extends about 7.4 million miles (12 million kilometers) beyond that.

9. The “Beyond Phase” pushes Spitzer to new limits.

In 2016, Spitzer entered its “Beyond phase,” with a name reflecting how the spacecraft operates beyond its original scope.

As Spitzer floats away from Earth, its increasing distance presents communication challenges. Engineers must point Spitzer’s antenna at higher angles toward the Sun in order to talk to our planet, which exposes the spacecraft to more heat. At the same time, the spacecraft’s solar panels receive less sunlight because they point away from the Sun, putting more stress on the battery.

The team decided to override some autonomous safety systems so Spitzer could continue to operate in this riskier mode. But so far, the Beyond phase is going smoothly.

10. Spitzer paves the way for future infrared telescopes.

Spitzer has identified areas of further study for our upcoming James Webb Space Telescope, planned to launch in 2021. Webb will also explore the universe in infrared light, picking up where Spitzer eventually will leave off. With its enhanced ability to probe planetary atmospheres, Webb may reveal striking new details about exoplanets that Spitzer found. Distant galaxies unveiled by Spitzer together with other telescopes will also be observed in further detail by Webb. The space telescope we are planning after that, WFIRST, will also investigate long-standing mysteries by looking at infrared light. Scientists planning studies with future infrared telescopes will naturally build upon the pioneering legacy of Spitzer.

Read the web version of this week’s “Solar System: 10 Things to Know” article HERE. 

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NASA’s Fleet of Planet-hunters and World-explorers

Around every star there could be at least one planet, so we’re bound to find one that is rocky, like Earth, and possibly suitable for life. While we’re not quite to the point where we can zoom up and take clear snapshots of the thousands of distant worlds we’ve found outside our solar system, there are ways we can figure out what exoplanets light years away are made of, and if they have signs of basic building blocks for life. Here are a few current and upcoming missions helping us explore new worlds:

Kepler

Launched in 2009, the Kepler space telescope searched for planets by looking for telltale dips in a star’s brightness caused by crossing, or transiting, planets. It has confirmed more than 1,000 planets; of these, fewer than 20 are Earth-size (therefore possibly rocky) and in the habitable zone -- the area around a star where liquid water could pool on the surface of an orbiting planet. Astronomers using Kepler data found the first Earth-sized planet orbiting in the habitable zone of its star and one in the habitable zone of a sun-like star.

In May 2013, a second pointing wheel on the spacecraft broke, making it not stable enough to continue its original mission. But clever engineers and scientists got to work, and in May 2014, Kepler took on a new job as the K2 mission. K2 continues the search for other worlds but has introduced new opportunities to observe star clusters, young and old stars, active galaxies and supernovae.

Transiting Exoplanet Survey Satellite (TESS)

Revving up for launch around 2017-2018, NASA’s Transiting Exoplanet Survey Satellite (TESS) will find new planets the same way Kepler does, but right in the stellar backyard of our solar system while covering 400 times the sky area. It plans to monitor 200,000 bright, nearby stars for planets, with a focus on finding Earth and Super-Earth-sized planets. 

Once we’ve narrowed down the best targets for follow-up, astronomers can figure out what these planets are made of, and what’s in the atmosphere. One of the ways to look into the atmosphere is through spectroscopy.  

As a planet passes between us and its star, a small amount of starlight is absorbed by the gas in the planet’s atmosphere. This leaves telltale chemical “fingerprints” in the star’s light that astronomers can use to discover the chemical composition of the atmosphere, such as methane, carbon dioxide, or water vapor. 

James Webb Space Telescope

Launching in 2018, NASA’s most powerful telescope to date, the James Webb Space Telescope (JWST), will not only be able to search for planets orbiting distant stars, its near-infrared multi-object spectrograph will split infrared light into its different colors- spectrum- providing scientists with information about an physical properties about an exoplanet’s atmosphere, including temperature, mass, and chemical composition. 

Hubble Space Telescope

Hubble Space Telescope is better than ever after 25 years of science, and has found evidence for atmospheres bleeding off exoplanets very close to their stars, and even provided thermal maps of exoplanet atmospheres. Hubble holds the record for finding the farthest exoplanets discovered to date, located 26,000 light-years away in the hub of our Milky Way galaxy.

Chandra X-ray Observatory

Chandra X-ray Observatory can detect exoplanets passing in front of their parent stars. X-ray observations can also help give clues on an exoplanet’s atmosphere and magnetic fields. It has observed an exoplanet that made its star act much older than it actually is. 

Spitzer Space Telescope

Spitzer Space Telescope has been unveiling hidden cosmic objects with its dust-piercing infrared vision for more than 12 years. It helped pioneer the study of atmospheres and weather on large, gaseous exoplanets. Spitzer can help narrow down the sizes of exoplanets, and recently confirmed the closest known rocky planet to Earth.

SOFIA

The Stratospheric Observatory for Infrared Astronomy (SOFIA) is an airplane mounted with an infrared telescope that can fly above more than 99 percent of Earth's atmospheric water vapor. Unlike most space observatories, SOFIA can be routinely upgraded and repaired. It can look at planetary-forming systems and has recently observed its first exoplanet transit. 

What’s Coming Next?

Analyzing the chemical makeup of Earth-sized, rocky planets with thin atmospheres is a big challenge, since smaller planets are incredibly faint compared to their stars. One solution is to block the light of the planets' glaring stars so that we can directly see the reflected light of the planets. Telescope instruments called coronagraphs use masks to block the starlight while letting the planet's light pass through. Another possible tool is a large, flower-shaped structure known as the starshade. This structure would fly in tandem with a space telescope to block the light of a star before it enters the telescope. 

All images (except SOFIA) are artist illustrations.

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