Largest Batch of Earth-size, Habitable Zone Planets

Our Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located in an area called the habitable zone, where liquid water is most likely to exist on a rocky planet.

This exoplanet system is called TRAPPIST-1, named for The Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile. In May 2016, researchers using TRAPPIST announced they had discovered three planets in the system.

Assisted by several ground-based telescopes, Spitzer confirmed the existence of two of these planets and discovered five additional ones, increasing the number of known planets in the system to seven.

This is the FIRST time three terrestrial planets have been found in the habitable zone of a star, and this is the FIRST time we have been able to measure both the masses and the radius for habitable zone Earth-sized planets.

All of these seven planets could have liquid water, key to life as we know it, under the right atmospheric conditions, but the chances are highest with the three in the habitable zone.

At about 40 light-years (235 trillion miles) from Earth, the system of planets is relatively close to us, in the constellation Aquarius. Because they are located outside of our solar system, these planets are scientifically known as exoplanets. To clarify, exoplanets are planets outside our solar system that orbit a sun-like star.

In this animation, you can see the planets orbiting the star, with the green area representing the famous habitable zone, defined as the range of distance to the star for which an Earth-like planet is the most likely to harbor abundant liquid water on its surface. Planets e, f and g fall in the habitable zone of the star.

Using Spitzer data, the team precisely measured the sizes of the seven planets and developed first estimates of the masses of six of them. The mass of the seventh and farthest exoplanet has not yet been estimated.

For comparison…if our sun was the size of a basketball, the TRAPPIST-1 star would be the size of a golf ball.

Based on their densities, all of the TRAPPIST-1 planets are likely to be rocky. Further observations will not only help determine whether they are rich in water, but also possibly reveal whether any could have liquid water on their surfaces.

The sun at the center of this system is classified as an ultra-cool dwarf and is so cool that liquid water could survive on planets orbiting very close to it, closer than is possible on planets in our solar system. All seven of the TRAPPIST-1 planetary orbits are closer to their host star than Mercury is to our sun.

 The planets also are very close to each other. How close? Well, if a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth’s sky.

The planets may also be tidally-locked to their star, which means the same side of the planet is always facing the star, therefore each side is either perpetual day or night. This could mean they have weather patterns totally unlike those on Earth, such as strong wind blowing from the day side to the night side, and extreme temperature changes.

Because most TRAPPIST-1 planets are likely to be rocky, and they are very close to one another, scientists view the Galilean moons of Jupiter – lo, Europa, Callisto, Ganymede – as good comparisons in our solar system. All of these moons are also tidally locked to Jupiter. The TRAPPIST-1 star is only slightly wider than Jupiter, yet much warmer. 

How Did the Spitzer Space Telescope Detect this System?

Spitzer, an infrared telescope that trails Earth as it orbits the sun, was well-suited for studying TRAPPIST-1 because the star glows brightest in infrared light, whose wavelengths are longer than the eye can see. Spitzer is uniquely positioned in its orbit to observe enough crossing (aka transits) of the planets in front of the host star to reveal the complex architecture of the system. 

Every time a planet passes by, or transits, a star, it blocks out some light. Spitzer measured the dips in light and based on how big the dip, you can determine the size of the planet. The timing of the transits tells you how long it takes for the planet to orbit the star.

The TRAPPIST-1 system provides one of the best opportunities in the next decade to study the atmospheres around Earth-size planets. Spitzer, Hubble and Kepler will help astronomers plan for follow-up studies using our upcoming James Webb Space Telescope, launching in 2018. With much greater sensitivity, Webb will be able to detect the chemical fingerprints of water, methane, oxygen, ozone and other components of a planet’s atmosphere.

At 40 light-years away, humans won’t be visiting this system in person anytime soon…that said…this poster can help us imagine what it would be like: 

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Stars reflect off a telescope in the Canary Islands as it pivots

Why do stars have four “arm-twinkles” that look like a cross coming out of the star?

Short answer: They don’t!

Longer answer: It’s actually light diffracting around the four arms (called spider legs) holding up the secondary mirror of a telescope! For the stars above it’s four spider legs from the stars because the Hubble Space Telescope took these images and its secondary mirror has four arms holding the secondary - for other telescopes the diffraction could be different depending on how the secondary mirror is held up.

Here’s apicture of the Hubble’s secondary mirror design:

Three of the four “spider arms” are visible and I drew red lines next to them so you could see what they look like.

(Image credit: NASA and ESA )

Infrared is Beautiful

Why was James Webb Space Telescope designed to observe infrared light? How can its images hope to compare to those taken by the (primarily) visible-light Hubble Space Telescope? The short answer is that Webb will absolutely capture beautiful images of the universe, even if it won’t see exactly what Hubble sees. (Spoiler: It will see a lot of things even better.)

The James Webb Space Telescope, or Webb, is our upcoming infrared space observatory, which will launch in 2019. It will spy the first luminous objects that formed in the universe and shed light on how galaxies evolve, how stars and planetary systems are born, and how life could form on other planets.

What is infrared light? 

This may surprise you, but your remote control uses light waves just beyond the visible spectrum of light—infrared light waves—to change channels on your TV.

Infrared light shows us how hot things are. It can also show us how cold things are. But it all has to do with heat. Since the primary source of infrared radiation is heat or thermal radiation, any object that has a temperature radiates in the infrared. Even objects that we think of as being very cold, such as an ice cube, emit infrared.

There are legitimate scientific reasons for Webb to be an infrared telescope. There are things we want to know more about, and we need an infrared telescope to learn about them. Things like: stars and planets being born inside clouds of dust and gas; the very first stars and galaxies, which are so far away the light they emit has been stretched into the infrared; and the chemical fingerprints of elements and molecules in the atmospheres of exoplanets, some of which are only seen in the infrared.

In a star-forming region of space called the ‘Pillars of Creation,’ this is what we see with visible light:

And this is what we see with infrared light:

Infrared light can pierce through obscuring dust and gas and unveil a more unfamiliar view.

Webb will see some visible light: red and orange. But the truth is that even though Webb sees mostly infrared light, it will still take beautiful images. The beauty and quality of an astronomical image depends on two things: the sharpness of the image and the number of pixels in the camera. On both of these counts, Webb is very similar to, and in many ways better than, Hubble. Webb will take much sharper images than Hubble at infrared wavelengths, and Hubble has comparable resolution at the visible wavelengths that Webb can see.

Webb’s infrared data can be translated by computer into something our eyes can appreciate – in fact, this is what we do with Hubble data. The gorgeous images we see from Hubble don’t pop out of the telescope looking fully formed. To maximize the resolution of the images, Hubble takes multiple exposures through different color filters on its cameras.

The separate exposures, which look black and white, are assembled into a true color picture via image processing. Full color is important to image analysis of celestial objects. It can be used to highlight the glow of various elements in a nebula, or different stellar populations in a galaxy. It can also highlight interesting features of the object that might be overlooked in a black and white exposure, and so the images not only look beautiful but also contain a lot of useful scientific information about the structure, temperatures, and chemical makeup of a celestial object.

This image shows the sequences in the production of a Hubble image of nebula Messier 17:

Here’s another compelling argument for having telescopes that view the universe outside the spectrum of visible light – not everything in the universe emits visible light. There are many phenomena which can only be seen at certain wavelengths of light, for example, in the X-ray part of the spectrum, or in the ultraviolet. When we combine images taken at different wavelengths of light, we can get a better understanding of an object, because each wavelength can show us a different feature or facet of it. 

Just like infrared data can be made into something meaningful to human eyes, so can each of the other wavelengths of light, even X-rays and gamma-rays.

Below is an image of the M82 galaxy created using X-ray data from the Chandra X-ray Observatory, infrared data from the Spitzer Space Telescope, and visible light data from Hubble. Also note how aesthetically pleasing the image is despite it not being just optical light:

Though Hubble sees primarily visible light, it can see some infrared. And despite not being optimized for it, and being much less powerful than Webb, it still produced this stunning image of the Horsehead Nebula.

It’s a big universe out there – more than our eyes can see. But with all the telescopes now at our disposal (as well as the new ones that will be coming online in the future), we are slowly building a more accurate picture. And it’s definitely a beautiful one. Just take a look…

…At this Spitzer infrared image of a shock wave in dust around the star Zeta Ophiuchi.

…this Spitzer image of the Helix Nebula, created using infrared data from the telescope and ultraviolet data from the Galaxy Evolution Explorer.

…this image of the “wing” of the Small Magellanic Cloud, created with infrared data from Spitzer and X-ray data from Chandra.

…the below image of the Milky Way’s galactic center, taken with our flying SOFIA telescope. It flies at more than 40,000 feet, putting it above 99% of the  water vapor in Earth’s atmosphere– critical for observing infrared because water vapor blocks infrared light from reaching the ground. This infrared view reveals the ring of gas and dust around a supermassive black hole that can’t be seen with visible light. 

…and this Hubble image of the Mystic Mountains in the Carina Nebula.

Learn more about the James Webb Space Telescope HERE, or follow the mission on FacebookTwitter and Instagram.

Image Credits
Eagle Nebula: NASA, ESA/Hubble and the Hubble Heritage Team
Hubble Image Processing - Messier 17: NASA/STScI
Galaxy M82 Composite Image: NASA, CXC, JHU, D.Strickland, JPL-Caltech, C. Engelbracht (University of Arizona), ESA, and The Hubble Heritage Team (STScI/AURA)
Horsehead Nebula: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)
Zeta Ophiuchi: NASA/JPL-Caltech
Helix Nebula: NASA/JPL-Caltech
Wing of the Small Magellanic Cloud
X-ray: NASA/CXC/Univ.Potsdam/L.Oskinova et al; Optical: NASA/STScI; Infrared: NASA/JPL-Caltech
Milky Way Circumnuclear Ring: NASA/DLR/USRA/DSI/FORCAST Team/ Lau et al. 2013
Mystic Mountains in the Carina Nebula: NASA/ESA/M. Livio & Hubble 20th Anniversary Team (STScI)

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Airglow waves. Do you you think our night sky is pitch black ? Have a look at this timelapse video. I captured it at Carnegie Las Campamas observatory. Those red waves are not clouds (!) - this is pretty intense airglow, which takes place in upper atmosphere. It’s very interesting to see how the waves move. While camera pans you will notice on the foreground both 6.5-m Magellan telescopes, as well as nicely setting Milky Way. I hope you’ll enjoy the view ! :) Music: “Airglow” by © Club 220

A Mesmerizing Model of Monster Black Holes

Just about every galaxy the size of our Milky Way (or bigger) has a supermassive black hole at its center. These objects are ginormous — hundreds of thousands to billions of times the mass of the Sun! Now, we know galaxies merge from time to time, so it follows that some of their black holes should combine too. But we haven’t seen a collision like that yet, and we don’t know exactly what it would look like. 

A new simulation created on the Blue Waters supercomputer — which can do 13 quadrillion calculations per second, 3 million times faster than the average laptop — is helping scientists understand what kind of light would be produced by the gas around these systems as they spiral toward a merger.

The new simulation shows most of the light produced around these two black holes is UV or X-ray light. We can’t see those wavelengths with our own eyes, but many telescopes can. Models like this could tell the scientists what to look for. 

You may have spotted the blank circular region between the two black holes. No, that’s not a third black hole. It’s a spot that wasn’t modeled in this version of the simulation. Future models will include the glowing gas passing between the black holes in that region, but the researchers need more processing power. The current version already required 46 days!

The supermassive black holes have some pretty nifty effects on the light created by the gas in the system. If you view the simulation from the side, you can see that their gravity bends light like a lens. When the black holes are lined up, you even get a double lens!

But what would the view be like from between two black holes? In the 360-degree video above, the system’s gas has been removed and the Gaia star catalog has been added to the background. If you watch the video in the YouTube app on your phone, you can moved the screen around to explore this extreme vista. Learn more about the new simulation here

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The animation shows the geocentric phase, libration, position angle of the axis, and apparent diameter of the Moon throughout the year 2017, at hourly intervals.
Credit: NASA/Goddard/LRO

Five Famous Pulsars from the Past 50 Years

Early astronomers faced an obstacle: their technology. These great minds only had access to telescopes that revealed celestial bodies shining in visible light. Later, with the development of new detectors, scientists opened their eyes to other types of light like radio waves and X-rays. They realized cosmic objects look very different when viewed in these additional wavelengths. Pulsars — rapidly spinning stellar corpses that appear to pulse at us — are a perfect example.

The first pulsar was observed 50 years ago on August 6, 1967, using radio waves, but since then we have studied them in nearly all wavelengths of light, including X-rays and gamma rays.

Typical Pulsar

Most pulsars form when a star — between 8 and 20 times the mass of our sun — runs out of fuel and its core collapses into a super dense and compact object: a neutron star

These neutron stars are about the size of a city and can rotate slowly or quite quickly, spinning anywhere from once every few hours to hundreds of times per second. As they whirl, they emit beams of light that appear to blink at us from space.

First Pulsar

One day five decades ago, a graduate student at the University of Cambridge, England, named Jocelyn Bell was poring over the data from her radio telescope - 120 meters of paper recordings.

Image Credit: Sumit Sijher

She noticed some unusual markings, which she called “scruff,” indicating a mysterious object (simulated above) that flashed without fail every 1.33730 seconds. This was the very first pulsar discovered, known today as PSR B1919+21.

Best Known Pulsar

Before long, we realized pulsars were far more complicated than first meets the eye — they produce many kinds of light, not only radio waves. Take our galaxy’s Crab Nebula, just 6,500 light years away and somewhat of a local celebrity. It formed after a supernova explosion, which crushed the parent star’s core into a neutron star. 

The resulting pulsar, nestled inside the nebula that resulted from the supernova explosion, is among the most well-studied objects in our cosmos. It’s pictured above in X-ray light, but it shines across almost the entire electromagnetic spectrum, from radio waves to gamma rays.

Brightest Gamma-ray Pulsar

Speaking of gamma rays, in 2015 our Fermi Gamma-ray Space Telescope discovered the first pulsar beyond our own galaxy capable of producing such high-energy emissions. 

Located in the Tarantula Nebula 163,000 light-years away, PSR J0540-6919 gleams nearly 20 times brighter in gamma-rays than the pulsar embedded in the Crab Nebula.

Dual Personality Pulsar

No two pulsars are exactly alike, and in 2013 an especially fast-spinning one had an identity crisis. A fleet of orbiting X-ray telescopes, including our Swift and Chandra observatories, caught IGR J18245-2452 as it alternated between generating X-rays and radio waves. 

Scientists suspect these radical changes could be due to the rise and fall of gas streaming onto the pulsar from its companion star.

Transformer Pulsar

This just goes to show that pulsars are easily influenced by their surroundings. That same year, our Fermi Gamma Ray Space Telescope uncovered another pulsar, PSR J1023+0038, in the act of a major transformation — also under the influence of its nearby companion star. 

The radio beacon disappeared and the pulsar brightened fivefold in gamma rays, as if someone had flipped a switch to increase the energy of the system. 

NICER Mission

Our Neutron star Interior Composition Explorer (NICER) mission, launched this past June, will study pulsars like those above using X-ray measurements.

With NICER’s help, scientists will be able to gaze even deeper into the cores of these dense and mysterious entities.

For more information about NICER, visit

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