Black holes are mystifying yet terrifying cosmic phenomena. Unfortunately, people have a lot of ideas about them that are more science fiction than science. Don’t worry! Our black hole expert, Jeremy Schnittman, will be answering your your questions in an Answer Time session on Wednesday, October 2 from 3pm - 4 pm ET here on NASA’s Tumblr! Make sure to ask your question now by visiting http://nasa.tumblr.com/ask!
Jeremy joined the Astrophysics Science Division at our Goddard Space Flight Center in 2010 following postdoctoral fellowships at the University of Maryland and Johns Hopkins University. His research interests include theoretical and computational modeling of black hole accretion flows, X-ray polarimetry, black hole binaries, gravitational wave sources, gravitational microlensing, dark matter annihilation, planetary dynamics, resonance dynamics and exoplanet atmospheres. He has been described as a “general-purpose astrophysics theorist,” which he regards as quite a compliment.
Fun Fact: The computer code Jeremy used to make the black hole animations we featured last week is called “Pandurata,” after a species of black orchid from Sumatra. The name pays homage to the laser fusion lab at the University of Rochester where Jeremy worked as a high school student and wrote his first computer code, “Buttercup.” All the simulation codes at the lab are named after flowers.
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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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Do you believe in magic? ✨ While appearing as a delicate and light veil draped across the sky, this @NASAHubble image reminds us of the power of imagination. What does this look like to you? In reality, it’s a small section of a Cygnus supernova blast wave, located around 2,400 light-years away. The original supernova explosion blasted apart a dying star about 20 times more massive than our Sun between 10,000 and 20,000 years ago. Since then, the remnant has expanded 60 light-years from its center. Credit: @ESA/Hubble & NASA, W. Blair; acknowledgment: Leo Shatz
Gravitational Waves in the Space-Time Continuum
Einstein's Theories of Relativity
Einstein has two theories of relativity. The first is The Theory of Special Relativity (1905). This is a theory of mechanics that correctly describes the motions of objects moving near the speed of light. This theory predicts that mass increases with velocity. The equation is E=MC^2 or Energy = Mass × Speed of Light ^2.
In 1916, Einstein proposed the Theory of General Relativity, which generalized his Theory of Special Relativity and had the first predictions of gravitational waves. It implied a few things.
Space-Time is a 4-Dimensional continuum.
Principle of equivalence of gravitational and inertial mass.
This suggests that Mass-Energy distorts the fabric of space-time in a predictable way (gravitational waves). It also implies
Strong gravitational force makes time slow down.
Light is altered by gravity
Gravity in strong gravitational fields will no longer obey Newton's Inverse-Square Law.
What is Newton's Inverse-Square Law?
Newton's Inverse-Square Law suggests that the force of gravity between any two objects is inversely proportional to the square of the separation distance between the two centers.
Stephen Hawking's Theory of Everything
Stephen Hawking's Theory of Everything is the solution to Einstein's equation in his Theory of General Relativity. It says that the mass density of the universe exceeds the critical density.
Critical Density: amount of mass needed to make a universe adopt a flat geometry.
This theory states that when the universe gets too big it will crash back into its center in a "Big Crunch" creating giant black hole. The energy from this "Big Crunch" will rebound and create a new "Big Bang".
Big Crunch: hypothetical scenario for the end of the known universe. The expansion of the universe will reverse and collapse on itself. The energy generated will create a new Big Bang, creating a new universe.
Big Bang: Matter will expand from a single point from a state of high density and matter. This will mark the birth of a new universe.
Basic Facts about Gravitational Waves
Invisible "ripples" in the Space-Time Continuum
Travel at the speed of light
186,000 miles per second / 299,337.984 Kilometers per second
11,160,000 miles per minute / 17,960,279.04 Kilometers per minute
669,600,000 miles per hour / 1,077,616,742.4 Kilometers per hour
There are four (4) defined categories
Continuous
Stochastic
Burst
Compact Binary Inspiral
What is LIGO?
The first proof of the existence of gravitational waves came in 1974. 20+ years after Einstein's death.
The first physical proof came in 2015, 100 years after his theory was published. The waves were detected by LIGO.
LIGO- Laser Interferometer Gravitational-Wave Observatory
The waves detected in 2015 came from 2 black holes that collided 1.3 billion years ago in the constellation Hydra. 1.3 billion years ago multicellular life was just beginning to spread on Earth, it was before the time of the dinosaurs!
Continuous Gravitational Waves
Produced by a single spinning massive object.
Caused by imperfections on the surface.
The spin rate of the object is constant. The waves are come at a continuous frequency.
Stochastic Gravitational Waves
Smalles waves
Hardest to detect
Possibly caused by remnants of gravitational radiation left over from the Big Bang
Could possibly allow us to look at the history of the Universe.
Small waves from every direction mixed together.
Burst Gravitational Waves
Never been detected.
Like ever.
Never ever.
Not once.
Nope
No
N E V E R
We don't know anything about them.
If we learn about them they could reveal the greatest revolutionary information about the universe.
Compact Binary Inspiral Gravitational Waves
All waves detected by LIGO fall into this category.
Produced by orbiting pairs of massive and dense objects. (Neutron Stars, Black Holes)
Three (3) subclasses
Binary Neutron Star (BNS) // Two (2) Neutron Stars colliding
Binary Black Hole (BBH) // Two (2) Black Holes colliding
Neutron Star- Black Hole Binary (NSBH) // A black hole and a neutron star colliding
Each subclass creates its own unique wave pattern.
Waves are all caused by the smae mechanism called an "inspiral".
Occur over millions of years.
Over eons the objects orbit closer together.
The closer they get, the faster they spin.
Sources Used:
On The Shoulders Of Giants by Stephen Hawking
Oxford Astronomy Encyclopedia
@watch-out-idiot-passing-through @nasa
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!
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.
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.
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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Did you know we help farmers grow some of your favorite fruits, veggies and grains?
Our Earth-observing satellites track rainfall amounts, soil moisture, crop health, and more. On the ground, we partner with agencies and organizations around the world to help farmers use that data to care for their fields.
Here are a few ways we help put food on the table, from planting to harvest.
Did you plant seeds in science class to watch them sprout and grow? They all needed water, right? Our data helps farmers “see” how moist the soil is across large fields.
“When you’re not sure when to water your flowers or your garden, you can look at the soil or touch it with your hands. We are sort of ‘feeling’ the soil, sensing how much water is in the soil – from a satellite,
685 kilometers (408 miles) above Earth,” said John Bolten, the associate program manager of water resources for NASA’s Applied Sciences Program.
This spring, we worked with the U.S. Department of Agriculture and George Mason University to release Crop-CASMA, a tool that shows soil moisture and vegetation conditions for the United States. Able to see smaller areas – about the size of a couple of golf courses – the USDA uses Crop-CASMA to help update farmers on their state’s soil moisture, crop health and growing progress.
It’s dangerous being a seedling.
Heavy spring rains or summer storms can flood fields and drown growing plants. Dry spells and droughts can starve them of nutrients. Insects and hail can damage them. Farmers need to keep a close eye on plants during the spring and summer months. Our data and programs help them do that.
For example, in California, irrigation is essential for agriculture. California’s Central Valley annually produces more than 250 types of crops and is one of the most productive agricultural regions in the country – but it’s dry. Some parts only get 6 inches of rain per year.
To help, Landsat data powers CropManage – an app that tells farmers how long to irrigate their fields, based on soil conditions and evapotranspiration, or how much water plants are releasing into the atmosphere. The warmer and drier the atmosphere, the more plants “sweat” and lose water that needs to be replenished. Knowing how long to irrigate helps farmers conserve water and be more efficient. In years like 2021, intense droughts can make water management especially critical.
Harvest
Leading up to harvest, farmers need to know their expected yields – and profits.
GEOGLAM, or the Group on Earth Observations Global Agricultural Monitoring Initiative, is a partnership between NASA Harvest, USDA’s Foreign Agricultural Service (FAS) and other global agencies to track and report on crop conditions around the world.
USDA FAS is one of the main users of a soil moisture measurement product developed by Bolten and his team at our NASA Goddard Space Flight Center to drive their crop forecasting system.
If you’re interested in more ways we support agriculture, stay tuned over the next few weeks to learn more about how satellites (and scientists) help put snacks on your table!
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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.
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.
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.
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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SHIELDS Up! NASA Rocket to Survey Our Solar System’s Windshield Apr 16, 2021
Eleven billion miles away – more than four times the distance from us to Pluto – lies the boundary of our solar system’s magnetic bubble, the heliopause. Here the Sun’s magnetic field, stretching through space like an invisible cobweb, fizzles to nothing. Interstellar space begins. “It’s really the largest boundary of its kind we can study,” said Walt Harris, space physicist at the University of Arizona in Tucson.
We still know little about what lies beyond this boundary. Fortunately, bits of interstellar space can come to us, passing right through this border and making their way into the solar system.
A new NASA mission will study light from interstellar particles that have drifted into our solar system to learn about the closest reaches of interstellar space. The mission, called the Spatial Heterodyne Interferometric Emission Line Dynamics Spectrometer, or SHIELDS, will have its first opportunity to launch aboard a suborbital rocket from the White Sands Missile Range in New Mexico on April 19, 2021.
Our entire solar system is adrift in a cluster of clouds, an area cleared by ancient supernova blasts. Astronomers call this region the Local Bubble, an oblong plot of space about 300 light-years long within the spiraling Orion arm of our Milky Way galaxy. It contains hundreds of stars, including our own Sun.
We fare this interstellar sea is our trusty vessel, the heliosphere, a much smaller (though still gigantic) magnetic bubble blown up by the Sun. As we orbit the Sun, the solar system itself, encased in the heliosphere, hurtles through the Local Bubble at about 52,000 miles per hour (23 kilometers per second). Interstellar particles pelt the nose of our heliosphere like rain against a windshield.
Our heliosphere is more like a rubber raft than a wooden sailboat: Its surroundings mold its shape. It compresses at points of pressure, expands where it gives way. Exactly how and where our heliosphere’s lining deforms gives us clues about the nature of the interstellar space outside it. This boundary – and any deformities in it – are what Walt Harris, principal investigator for the SHIELDS mission, is after.
SHIELDS is a telescope that will launch aboard a sounding rocket, a small vehicle that flies to space for a few minutes of observing time before falling back to Earth. Harris’ team launched an earlier iteration of the telescope as part of the HYPE mission in 2014, and after modifying the design, they’re ready to launch again.
SHIELDS will measure light from a special population of hydrogen atoms originally from interstellar space. These atoms are neutral, with a balanced number of protons and electrons. Neutral atoms can cross magnetic field lines, so they seep through the heliopause and into our solar system nearly unfazed – but not completely.
The small effects of this boundary crossing are key to SHIELDS’s technique. Charged particles flow around the heliopause, forming a barrier. Neutral particles from interstellar space must pass through this gauntlet, which alters their paths. SHIELDS was designed to reconstruct the trajectories of the neutral particles to determine where they came from and what they saw along the way.
A few minutes after launch, SHIELDS will reach its peak altitude of about 186 miles (300 kilometers) from the ground, far above the absorbing effect of Earth’s atmosphere. Pointing its telescope towards the nose of the heliosphere, it will detect light from arriving hydrogen atoms. Measuring how that light’s wavelength stretches or contracts reveals the particles’ speed. All told, SHIELDS will produce a map to reconstruct the shape and varying density of matter at the heliopause.
The data, Harris hopes, will help answer tantalizing questions about what interstellar space is like.
For instance, astronomers think the Local Bubble as a whole is about 1/10th as dense as most of the rest of the galaxy’s main disk. But we don’t know the details – for instance, is matter in the Local Bubble is distributed evenly, or bunched up in dense pockets surrounded by nothingness? “There’s a lot of uncertainty about the fine structure of the interstellar medium – our maps are kind of crude,” Harris said. “We know the general outlines of these clouds, but we don’t know what’s happening inside them.”
Astronomers also don’t know much about the galaxy’s magnetic field. But it should leave a mark on our heliosphere that SHIELDS can detect, compressing the heliopause in a specific way based on its strength and orientation.
Finally, learning what our current plot of interstellar space is like could be a helpful guide for the (distant) future. Our solar system is just passing through our current patch of space. In some 50,000 years, we’ll be on our way out of the Local Bubble and on to who knows what.
“We don’t really know what that other cloud is like, and we don’t know what happens when you cross a boundary into that cloud,” Harris said. “There’s a lot of interest in understanding what we’re likely to experience as our solar system makes that transition.”
Not that our solar system hasn’t done it before. Over the last four billion years, Harris explains, Earth has passed through a variety of interstellar environments. It’s just that now we’re around, with the scientific tools to document it.
“We’re just trying to understand our place in the galaxy, and where we’re headed in the future,” Harris said.
TOP IMAGE….An illustration of the heliosphere being pelted with cosmic rays from outside our solar system. Credit: NASA’s Goddard Space Flight Center/Conceptual Image Lab
LOWER IMAGE….Illustration of the Local Bubble. Credits: NASA’s Goddard Space Flight Center