Science-child - Space Boii

I hope you will enjoy this Halloween special. Today, we are trying something a little bit different by exploring the evolution of a particular animal : Bats.

While their evolutionary history is shrouded in mystery, they allow us, nonetheless, to explore 2 interesting ideas :

1- Convergent evolution : How organisms tend to evolve similar (albeit not identical) body plans as solutions to similar problems (flight in birds, bats and pterosaurs)

2- Prediction : Like any theory, evolution is not only descriptive, but also predictive. Thanks to its models and principles, it allows us to make predictions to complement our gap in observational data.

Happy Halloween!

P.S. : The blog in the third picture is neither scientific nor peer-reviewed. But it is a nice illustration of how the common ancestor of bats MIGHT have looked like, and how using basic principles from evolution, phylogeny, and comparative anatomy, we can visualize how some animals have come to be what they are.

Sea Level Rise is on the Rise

As our planet warms, sea levels are rising around the world – and are doing so at an accelerating rate. Currently, global sea level is rising about an eighth of an inch every year.

That may seem insignificant, but it’s 30% more than when NASA launched its first satellite mission to measure ocean heights in 1992 – less than 30 years ago. And people already feel the impacts, as seemingly small increments of sea level rise become big problems along coastlines worldwide.

Higher global temperatures cause our seas to rise, but how? And why are seas rising at a faster and faster rate? There are two main reasons: melting ice and warming waters.

 The Ice We See Is Getting Pretty Thin

About two-thirds of global sea level rise comes from melting glaciers and ice sheets, the vast expanses of ice that cover Antarctica and Greenland. In Greenland, most of that ice melt is caused by warmer air temperatures that melt the upper surface of ice sheets, and when giant chunks of ice crack off of the ends of glaciers, adding to the ocean.

In Antarctica – where temperatures stay low year-round – most of the ice loss happens at the edges of glaciers. Warmer ocean water and warmer air meet at the glaciers’ edges, eating away at the floating ice sheets there.

NASA can measure these changes from space. With data from the Ice, Cloud and land Elevation Satellite-2, or ICESat-2, scientists can measure the height of ice sheets to within a fraction of an inch. Since 2006, an average of 318 gigatons of ice per year has melted from Greenland and Antarctica’s ice sheets. To get a sense of how big that is: just one gigaton is enough to cover New York City’s Central Park in ice 1,000 feet deep – almost as tall as the Chrysler Building.

With the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission – a partnership with the German Research Centre for Geosciences – scientists can calculate the mass of ice lost from these vast expanses across Greenland and Antarctica.

It’s not just glaciers in Antarctica and Greenland that are melting, though. Nearly all glaciers have been melting in the last decade, including those in Alaska, High Mountain Asia, South America, and the Canadian Arctic. Because these smaller glaciers are melting quickly, they contribute about the same amount to sea level rise as meltwater from massive ice sheets.

The Water’s Getting Warm

As seawater warms, it takes up more space. When water molecules get warmer, the atoms in those molecules vibrate faster, expanding the volume they take up. This phenomenon is called thermal expansion. It’s an incredibly tiny change in the size of a single water molecule, but added across all the water molecules in all of Earth’s oceans – a single drop contains well over a billion billion molecules – it accounts for about a third of global sea level rise.

So Much to See

While sea level is rising globally, it’s not the same across the planet. Sea levels are rising about an eighth of an inch per year on average worldwide. But some areas may see triple that rate, some may not observe any changes, and some may even experience a drop in sea level. These differences are due to ocean currents, mixing, upwelling of cold water from the deep ocean, winds, movements of heat and freshwater, and Earth’s gravitational pull moving water around. When ice melts from Greenland, for example, the drop in mass decreases the gravitational pull from the ice sheet, causing water to slosh to the shores of South America.

That’s where our view from space comes in. We’re launching Sentinel-6 Michael Freilich, an international partnership satellite, to continue our decades-long record of global sea level rise.

Who Was Mary W. Jackson?

On June 24, 2020, NASA announced the agency’s headquarters building in Washington, D.C., was to be named after Mary W. Jackson, the first African American female engineer at NASA.

Jackson’s story — along with those of her colleagues Katherine Johnson, Dorothy Vaughan, and Christine Darden — was popularized with the release of the “Hidden Figures” movie, based on Margot Lee Shetterly’s book by the same name.

Today, as the accomplishments of these women are brought to light, we celebrate them as Modern Figures — hidden no longer. Despite their recent recognition, we cannot forget the challenges that women and BIPOC faced and continue to face in the STEM fields.

Background

Jackson showed talent for math and science at an early age. She was born in 1921 in Hampton, Virginia, and attended the all-Black George P. Phenix Training School where she graduated with honors. She graduated from Hampton Institute (now Hampton University) in 1942 with a bachelor of science degree in both mathematics and physical sciences.

Jackson worked several jobs before arriving at the National Advisory Committee on Aeronautics (NACA), the precursor organization to NASA. She was a teacher, a receptionist, and a bookkeeper — in addition to becoming a mother — before accepting a position with the NACA Langley Aeronautical Laboratory’s segregated West Area Computers in 1951, where her supervisor was Dorothy Vaughan.

Accomplishments 

After two years in West Computing, Jackson was offered a computing position to work in the 4-foot by 4-foot Supersonic Pressure Tunnel. She was also encouraged to enter a training program that would put her on track to become an engineer — however, she needed special permission from the City of Hampton to take classes in math and physics at then-segregated Hampton High School.

She completed the courses, earned the promotion, and in 1958 became NASA’s first African-American female engineer. That same year, she co-authored her first report, “Effects of Nose Angle and Mach Number on Transition on Cones at Supersonic Speeds.” By 1975, she had authored or co-authored 12 NACA and NASA technical publications — most focused on the behavior of the boundary layer of air around an airplane.

Legacy

Jackson eventually became frustrated with the lack of management opportunities for women in her field. In 1979, she left engineering to become NASA Langley’s Federal Women’s Program Manager to increase the hiring and promotion of NASA’s female mathematicians, engineers, and scientists.

Not only was she devoted to her career, Jackson was also committed to the advancement of her community. In the 1970s, she helped the students in the Hampton King Street Community Center build their own wind tunnel and run experiments. She and her husband Levi took in young professionals in need of guidance. She was also a Girl Scout troop leader for more than three decades.  

Jackson retired from Langley in 1985. Never accepting the status quo, she dedicated her life to breaking barriers for minorities in her field. Her legacy reminds us that inclusion and diversity are needed to live up to NASA’s core values of teamwork and excellence.

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The Great Conjunction of Jupiter and Saturn

Credits:  NASA/Bill Ingalls

Have you noticed two bright objects in the sky getting closer together with each passing night? It’s Jupiter and Saturn doing a planetary dance that will result in the Great Conjunction on Dec. 21. On that day, Jupiter and Saturn will be right next to each other in the sky – the closest they have appeared in nearly 400 years!

Skywatching Tips from NASA

Credits: NASA/JPL-Caltech

For those who would like to see this phenomenon for themselves, here’s what to do:

Find a spot with an unobstructed view of the sky, such as a field or park. Jupiter and Saturn are bright, so they can be seen even from most cities.

An hour after sunset, look to the southwestern sky. Jupiter will look like a bright star and be easily visible. Saturn will be slightly fainter and will appear slightly above and to the left of Jupiter until December 21, when Jupiter will overtake it and they will reverse positions in the sky.

The planets can be seen with the unaided eye, but if you have binoculars or a small telescope, you may be able to see Jupiter’s four large moons orbiting the giant planet.

How to Photograph the Conjunction

Credits: NASA/Bill Dunford

Saturn and Jupiter are easy to see without special equipment, and can be photographed easily on DSLR cameras and many cell phone cameras. Here are a few tips and tricks:

These planets are visible in the early evening, and you’ll have about 1-2 hours from when they are visible, to when they set. A photo from the same location can look completely different just an hour later!

Using a tripod will help you hold your camera steady while taking longer exposures. If you don’t have a tripod, brace your camera against something – a tree, a fence, or a car can all serve as a tripod for a several-second exposure.

The crescent Moon will pass near Jupiter and Saturn a few days before the conjunction. Take advantage of it in your composition!

Get more tips HERE.

Still have questions about the Great Conjunction?

Our NASA expert answered questions from social media on an episode of NASA Science Live on Thursday, Dec. 17. Watch the recording HERE.

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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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Physics meme

The Stellar Buddy System

Our Sun has an entourage of planets, moons, and smaller objects to keep it company as it traverses the galaxy. But it’s still lonely compared to many of the other stars out there, which often come in pairs. These cosmic couples, called binary stars, are very important in astronomy because they can easily reveal things that are much harder to learn from stars that are on their own. And some of them could even host habitable planets!

The birth of a stellar duo

New stars emerge from swirling clouds of gas and dust that are peppered throughout the galaxy. Scientists still aren’t sure about all the details, but turbulence deep within these clouds may give rise to knots that are denser than their surroundings. The knots have stronger gravity, so they can pull in more material and the cloud may begin to collapse.

The material at the center heats up. Known as a protostar, it is this hot core that will one day become a star. Sometimes these spinning clouds of collapsing gas and dust may break up into two, three, or even more blobs that eventually become stars. That would explain why the majority of the stars in the Milky Way are born with at least one sibling.

Seeing stars

We can’t always tell if we’re looking at binary stars using just our eyes. They’re often so close together in the sky that we see them as a single star. For example, Sirius, the brightest star we can see at night, is actually a binary system (see if you can spot both stars in the photo above). But no one knew that until the 1800s.

Precise observations showed that Sirius was swaying back and forth like it was at a middle school dance. In 1862, astronomer Alvan Graham Clark used a telescope to see that Sirius is actually two stars that orbit each other.

But even through our most powerful telescopes, some binary systems still masquerade as a single star. Fortunately there are a couple of tricks we can use to spot these pairs too.

Since binary stars orbit each other, there’s a chance that we’ll see some stars moving toward and away from us as they go around each other. We just need to have an edge-on view of their orbits. Astronomers can detect this movement because it changes the color of the star’s light – a phenomenon known as the Doppler effect.

Stars we can find this way are called spectroscopic binaries because we have to look at their spectra, which are basically charts or graphs that show the intensity of light being emitted over a range of energies. We can spot these star pairs because light travels in waves. When a star moves toward us, the waves of its light arrive closer together, which makes its light bluer. When a star moves away, the waves are lengthened, reddening its light.

Sometimes we can see binary stars when one of the stars moves in front of the other. Astronomers find these systems, called eclipsing binaries, by measuring the amount of light coming from stars over time. We receive less light than usual when the stars pass in front of each other, because the one in front will block some of the farther star’s light.

Sibling rivalry

Twin stars don’t always get along with each other – their relationship may be explosive! Type Ia supernovae happen in some binary systems in which a white dwarf – the small, hot core left over when a Sun-like star runs out of fuel and ejects its outer layers – is stealing material away from its companion star. This results in a runaway reaction that ultimately detonates the thieving star. The same type of explosion may also happen when two white dwarfs spiral toward each other and collide. Yikes!

Scientists know how to determine how bright these explosions should truly be at their peak, making Type Ia supernovae so-called standard candles. That means astronomers can determine how far away they are by seeing how bright they look from Earth. The farther they are, the dimmer they appear. Astronomers can also look at the wavelengths of light coming from the supernovae to find out how fast the dying stars are moving away from us.

Studying these supernovae led to the discovery that the expansion of the universe is speeding up. Our Nancy Grace Roman Space Telescope will scan the skies for these exploding stars when it launches in the mid-2020s to help us figure out what’s causing the expansion to accelerate – a mystery known as dark energy.

Spilling stellar secrets

Astronomers like finding binary systems because it’s a lot easier to learn more about stars that are in pairs than ones that are on their own. That’s because the stars affect each other in ways we can measure. For example, by paying attention to how the stars orbit each other, we can determine how massive they are. Since heavier stars burn hotter and use up their fuel more quickly than lighter ones, knowing a star’s mass reveals other interesting things too.

By studying how the light changes in eclipsing binaries when the stars cross in front of each other, we can learn even more! We can figure out their sizes, masses, how fast they’re each spinning, how hot they are, and even how far away they are. All of that helps us understand more about the universe.

Tatooine worlds

Thanks to observatories such as our Kepler Space Telescope, we know that worlds like Luke Skywalker’s home planet Tatooine in “Star Wars” exist in real life. And if a planet orbits at the right distance from the two stars, it could even be habitable (and stay that way for a long time).

In 2019, our Transiting Exoplanet Survey Satellite (TESS) found a planet, known as TOI-1338 b, orbiting a pair of stars. These worlds are tricker to find than planets with only one host star, but TESS is expected to find several more!

Want to learn more about the relationships between stellar couples? Check out this Tumblr post: https://nasa.tumblr.com/post/190824389279/cosmic-couples-and-devastating-breakups

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"I used to measure the heavens; now I shall measure the shadows of the earth. Although my soul was from heaven, the shadow of my body lies here."

-Johannes Kepler-

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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