Did you know some of the brightest sources of light in the sky come from black holes in the centers of galaxies? It sounds a little contradictory, but it's true! They may not look bright to our eyes, but satellites have spotted oodles of them across the universe.
One of those satellites is our Fermi Gamma-ray Space Telescope. Fermi has found thousands of these kinds of galaxies in the 10 years it's been operating, and there are many more out there!
Black holes are regions of space that have so much gravity that nothing - not light, not particles, nada - can escape. Most galaxies have supermassive black holes at their centers - these are black holes that are hundreds of thousands to billions of times the mass of our sun - but active galactic nuclei (also called "AGN" for short, or just "active galaxies") are surrounded by gas and dust that's constantly falling into the black hole. As the gas and dust fall, they start to spin and form a disk. Because of the friction and other forces at work, the spinning disk starts to heat up.
The disk's heat gets emitted as light - but not just wavelengths of it that we can see with our eyes. We see light from AGN across the entire electromagnetic spectrum, from the more familiar radio and optical waves through to the more exotic X-rays and gamma rays, which we need special telescopes to spot.
About one in 10 AGN beam out jets of energetic particles, which are traveling almost as fast as light. Scientists are studying these jets to try to understand how black holes - which pull everything in with their huge amounts of gravity - somehow provide the energy needed to propel the particles in these jets.
Many of the ways we tell one type of AGN from another depend on how they're oriented from our point of view. With radio galaxies, for example, we see the jets from the side as they're beaming vast amounts of energy into space. Then there's blazars, which are a type of AGN that have a jet that is pointed almost directly at Earth, which makes the AGN particularly bright.
Our Fermi Gamma-ray Space Telescope has been searching the sky for gamma ray sources for 10 years. More than half (57%) of the sources it has found have been blazars. Gamma rays are useful because they can tell us a lot about how particles accelerate and how they interact with their environment.
So why do we care about AGN? We know that some AGN formed early in the history of the universe. With their enormous power, they almost certainly affected how the universe changed over time. By discovering how AGN work, we can understand better how the universe came to be the way it is now.
Fermi's helped us learn a lot about the gamma-ray universe over the last 10 years. Learn more about Fermi and how we're celebrating its accomplishments all year.
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You probably think this post is about you. Well, it could be.
In this image taken by our Hubble Space Telescope, we see a spiral galaxy with arms that widen as they whirl outward from its bright core, slowly fading into the emptiness of space. Click here to learn more about this beautiful galaxy that resides 70 million light-years away.
Credit: ESA/Hubble & NASA, L. Ho Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.
This month is filled with exciting celestial sights. Here are 10 targets you can view this month:
10. Unusual Sunset
During a sunset, our thick atmosphere absorbs most colors of sunlight, but red light is absorbed the least. Rarely, green flashes can be seen just above the sun’s edge. As the last sliver of the disk disappears below the horizon, be sure to watch its color.
9. Belt of Venus
Just after sunset, turn around and face east. A dark shadow will move up from the horizon and gradually cover the pinkish sky. This is caused from the Earth itself blocking the sunlight and is called the Earth Shadow or the Belt of Venus.
8. Crepuscular Rays
Also just after sunset, or before dawn, you may see rays of sunlight spread like a fan. These are called crepuscular rays and are formed when sunlight streams through gaps in the clouds or mountains.
7. Aurora Borealis
The northern lights, also known as the aurora borealis, are caused by collisions between gaseous particles in Earth’s atmosphere and charged particles released from the sun. The color of the lights can changed depending on the type of gas being struck by particles of solar wind. You can find out when and where to expect aurorae at the Space Weather Prediction Center.
6. Andromeda Galaxy
Did you now that The Andromeda Galaxy is one of the few you can actually see with your naked eye? In October, look nearly overhead after sunset to see it! This galaxy is more than twice the apparent width of the moon.
5. Moon Features
Nights in mid-October are excellent for viewing the features on the moon. Areas like the Sea of Tranquility and the site of the 1969 Apollo 11 landing will be visible.
4. A Comet
This month, the European Space Agency’s Rosetta mission target, a comet with a complicated name (Comet 67P Churyumov-Gerasimenko), is still bright enough for experienced astronomers to pick out in a dark sky. On October 9, you may be able to spot it in the east near the crescent moon and Venus.
3. Meteor Showers
There are multiple meteor showers this month. On the 9th: watch the faint, slow-moving Draconids. On the 10th: catch the slow, super-bright Taurids. And on the 21st: don’t’ miss the swift and bright Orionids from the dust of Comet Halley.
2. Three Close Planets
On October 28, you’ll find a tight grouping of Jupiter, Venus and Mars in the eastern sky before sunrise.
1. Zodiacal Light
The Zodiacal light is a faint triangular glow that can be seen from a dark sky after sunset or before sunrise. What you’re seeing is sunlight reflecting off dust grains that circle the sun in the inner solar system. These dust grains travel in the same plane as the moon and planets as they journey across our sky.
For more stargazing tools visit: Star Tool Box
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Today marks astronaut Scott Kelly’s 300th day in space! He, along with Russian cosmonaut Mikhail Kornienko, are testing the limits of human research during their one-year mission onboard the International Space Station.
While most expeditions to the space station last four to six months, their time on orbit has been doubled. By increasing the length of their time in space, researchers hope to better understand how the human body reacts and adapts to long-duration spaceflight.
1. You might get bored and play ping pong with yourself…and a water droplet.
2. There’s a chance that you’ll get a Tweet from someone famous…like the President!
3. There may come a time where you’ll have to fix something outside the station during a spacewalk.
4. You might develop a ‘green thumb’ and grow plants in space.
5. And, there’s no doubt you get to see the Earth from a totally new perspective.
To learn more about the one-year mission, visit: https://www.nasa.gov/1ym
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What's Up for May? Two huge solar system highlights: Mercury transits the sun and Mars is closer to Earth than it has been in 11 years.
On May 9, wake up early on the west coast or step out for coffee on the east coast to see our smallest planet cross the face of the sun. The transit will also be visible from most of South America, western Africa and western Europe.
A transit occurs when one astronomical body appears to move across the face of another as seen from Earth or from a spacecraft. But be safe! You'll need to view the sun and Mercury through a solar filter when looking through a telescope or when projecting the image of the solar disk onto a safe surface. Look a little south of the sun's Equator. It will take about 7 1/2 hours for the tiny planet's disk to cross the sun completely. Since Mercury is so tiny it will appear as a very small round speck, whether it's seen through a telescope or projected through a solar filter. The next Mercury transit will be Nov. 11, 2019.
Two other May highlights involve Mars. On May 22 Mars opposition occurs. That's when Mars, Earth and the sun all line up, with Earth directly in the middle.
Eight days later on May 30, Mars and Earth are nearest to each other in their orbits around the sun. Mars is over half a million miles closer to Earth at closest approach than at opposition. But you won't see much change in the diameter and brightness between these two dates. As Mars comes closer to Earth in its orbit, it appears larger and larger and brighter and brighter.
During this time Mars rises after the sun sets. The best time to see Mars at its brightest is when it is highest in the sky, around midnight in May and a little earlier in June.
Through a telescope you can make out some of the dark features on the planet, some of the lighter features and sometimes polar ice and dust storm-obscured areas showing very little detail.
After close approach, Earth sweeps past Mars quickly. So the planet appears large and bright for only a couple weeks.
But don't worry if you miss 2016's close approach. 2018's will be even better, as Mars' close approach will be, well, even closer.
You can find out about our #JourneytoMars missions at mars.nasa.gov, and you can learn about all of our missions at http://www.nasa.gov.
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We can agree that nebulae are some of the most majestic-looking objects in the universe. But what are they exactly? Nebulae are giant clouds of gas and dust in space. They’re commonly associated with two parts of the life cycle of stars: First, they can be nurseries forming new baby stars. Second, expanding clouds of gas and dust can mark where stars have died.
Not all nebulae are alike, and their different appearances tell us what's happening around them. Since not all nebulae emit light of their own, there are different ways that the clouds of gas and dust reveal themselves. Some nebulae scatter the light of stars hiding in or near them. These are called reflection nebulae and are a bit like seeing a street lamp illuminate the fog around it.
In another type, called emission nebulae, stars heat up the clouds of gas, whose chemicals respond by glowing in different colors. Think of it like a neon sign hanging in a shop window!
Finally there are nebulae with dust so thick that we’re unable to see the visible light from young stars shine through it. These are called dark nebulae.
Our missions help us see nebulae and identify the different elements that oftentimes light them up.
The Hubble Space Telescope is able to observe the cosmos in multiple wavelengths of light, ranging from ultraviolet, visible, and near-infrared. Hubble peered at the iconic Eagle Nebula in visible and infrared light, revealing these grand spires of dust and countless stars within and around them.
The Chandra X-ray Observatory studies the universe in X-ray light! The spacecraft is helping scientists see features within nebulae that might otherwise be hidden by gas and dust when viewed in longer wavelengths like visible and infrared light. In the Crab Nebula, Chandra sees high-energy X-rays from a pulsar (a type of rapidly spinning neutron star, which is the crushed, city-sized core of a star that exploded as a supernova).
The James Webb Space Telescope will primarily observe the infrared universe. With Webb, scientists will peer deep into clouds of dust and gas to study how stars and planetary systems form.
The Spitzer Space Telescope studied the cosmos for over 16 years before retiring in 2020. With the help of its detectors, Spitzer revealed unknown materials hiding in nebulae — like oddly-shaped molecules and soot-like materials, which were found in the California Nebula.
Studying nebulae helps scientists understand the life cycle of stars. Did you know our Sun got its start in a stellar nursery? Over 4.5 billion years ago, some gas and dust in a nebula clumped together due to gravity, and a baby Sun was born. The process to form a baby star itself can take a million years or more!
After billions more years, our Sun will eventually puff into a huge red giant star before leaving behind a beautiful planetary nebula (so-called because astronomers looking through early telescopes thought they resembled planets), along with a small, dense object called a white dwarf that will cool down very slowly. In fact, we don’t think the universe is old enough yet for any white dwarfs to have cooled down completely.
Since the Sun will live so much longer than us, scientists can't observe its whole life cycle directly ... but they can study tons of other stars and nebulae at different phases of their lives and draw conclusions about where our Sun came from and where it's headed. While studying nebulae, we’re seeing the past, present, and future of our Sun and trillions of others like it in the cosmos.
To keep up with the most recent cosmic news, follow NASA Universe on Twitter and Facebook.
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You are seeing the culmination of almost twenty years of rain and snow, all at once.
For the first time, we have combined and remastered the satellite measurements from two of our precipitation spacecraft to create our most detailed picture of our planet’s rain and snowfall. This new record will help scientists better understand normal and extreme rain and snowfall around the world and how these weather events may change in a warming climate.
Using this new two-decade record, we can see the most extreme places on Earth.
The wettest places on our planet occur over oceans. These extremely wet locations tend to be very concentrated and over small regions.
A region off the coast of Indonesia receives on average 279 inches of rain per year.
An area off the coast of Colombia sees on average 360 inches of rain per year.
The driest places on Earth are more widespread. Two of the driest places on Earth are also next to cold ocean waters. In these parts of the ocean, it rains as little as it does in the desert -- they’re also known as ocean deserts!
Just two thousand miles to the south of Colombia is one of the driest areas, the Atacama Desert in Chile that receives on average 0.64 inches of rain per year.
Across the Atlantic Ocean, Namibia experiences on average 0.49 inches of rain a year and Egypt gets on average 0.04 inches of rain per year.
As we move from January to December, we can see the seasons shift across the world.
During the summer in the Northern Hemisphere, massive monsoons move over India and Southeast Asia.
We can also see dynamic swirling patterns in the Southern Ocean, which scientists consider one of our planet’s last great unknowns.
This new record also reveals typical patterns of rain and snow at different times of the day -- a pattern known as the diurnal cycle.
As the Sun heats up Earth’s surface during the day, rainfall occurs over land. In Florida, sea breezes from the Gulf of Mexico and Atlantic Ocean feed the storms causing them to peak in the afternoon. At night, storms move over the ocean.
In the winter months in the U.S. west coast, the coastal regions generally receive similar amounts of rain and snow throughout the day. Here, precipitation is driven less from the daily heating of the Sun and more from the Pacific Ocean bringing in atmospheric rivers -- corridors of intense water vapor in the atmosphere.
This new record marks a major milestone in the effort to generate a long-term record of rain and snow. Not only does this long record improve our understanding of rain and snow as our planet changes, but it is a vital tool for other agencies and researchers to understand and predict floods, landslides, disease outbreaks and agricultural production.
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I’m on day 321 of my #YearInSpace, and today I surpassed 500 days in space total. Let’s chat! Sat., Feb. 13 at 1:45 p.m. ET.
The Voyager 1 and 2 spacecraft explored Jupiter, Saturn, Uranus and Neptune before starting their journey toward interstellar space. Here you’ll find some of those images, including “The Pale Blue Dot” – famously described by Carl Sagan – and what are still the only up-close images of Uranus and Neptune.
These twin spacecraft took some of the very first close-up images of these planets and paved the way for future planetary missions to return, like the Juno spacecraft at Jupiter, Cassini at Saturn and New Horizons at Pluto.
Photography of Jupiter began in January 1979, when images of the brightly banded planet already exceeded the best taken from Earth. They took more than 33,000 pictures of Jupiter and its five major satellites.
Findings:
Erupting volcanoes on Jupiter's moon Io, which has 100 times the volcanic activity of Earth.
Better understanding of important physical, geological, and atmospheric processes happening in the planet, its satellites and magnetosphere.
Jupiter's turbulent atmosphere with dozens of interacting hurricane-like storm systems.
The Saturn encounters occurred nine months apart, in November 1980 and August 1981. The two encounters increased our knowledge and altered our understanding of Saturn. The extended, close-range observations provided high-resolution data far different from the picture assembled during centuries of Earth-based studies.
Findings:
Saturn’s atmosphere is almost entirely hydrogen and helium.
Subdued contrasts and color differences on Saturn could be a result of more horizontal mixing or less production of localized colors than in Jupiter’s atmosphere.
An indication of an ocean beneath the cracked, icy crust of Jupiter's moon Europa.
Winds blow at high speeds in Saturn. Near the equator, the Voyagers measured winds about 1,100 miles an hour.
The Voyager 2 spacecraft flew closely past distant Uranus, the seventh planet from the Sun. At its closest, the spacecraft came within 50,600 miles of Uranus’s cloud tops on Jan. 24, 1986. Voyager 2 radioed thousands of images and voluminous amounts of other scientific data on the planet, its moons, rings, atmosphere, interior and the magnetic environment surrounding Uranus.
Findings:
Revealed complex surfaces indicative of varying geologic pasts.
Detected 11 previously unseen moons.
Uncovered the fine detail of the previously known rings and two newly detected rings.
Showed that the planet’s rate of rotation is 17 hours, 14 minutes.
Found that the planet’s magnetic field is both large and unusual.
Determined that the temperature of the equatorial region, which receives less sunlight over a Uranian year, is nevertheless about the same as that at the poles.
Voyager 2 became the first spacecraft to observe the planet Neptune in the summer of 1989. Passing about 3,000 miles above Neptune’s north pole, Voyager 2 made its closest approach to any planet since leaving Earth 12 years ago. Five hours later, Voyager 2 passed about 25,000 miles from Neptune’s largest moon, Triton, the last solid body the spacecraft had the opportunity to study.
Findings:
Discovered Neptune’s Great Dark Spot
Found that the planet has strong winds, around 1,000 miles per hour
Saw geysers erupting from the polar cap on Neptune’s moon Triton at -390 degrees Fahrenheit
This narrow-angle color image of the Earth, dubbed ‘Pale Blue Dot’, is a part of the first ever ‘portrait’ of the solar system taken by Voyager 1.
The spacecraft acquired a total of 60 frames for a mosaic of the solar system from a distance of more than 4 billion miles from Earth and about 32 degrees above the ecliptic.
From Voyager’s great distance, Earth is a mere point of light, less than the size of a picture element even in the narrow-angle camera.
“Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives.” - Carl Sagan
Both spacecraft will continue to study ultraviolet sources among the stars, and their fields and particles detectors will continue to search for the boundary between the Sun's influence and interstellar space. The radioisotope power systems will likely provide enough power for science to continue through 2025, and possibly support engineering data return through the mid-2030s. After that, the two Voyagers will continue to orbit the center of the Milky Way.
Learn more about the Voyager spacecraft HERE.
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The journey to Mars crosses three thresholds, each with increasing challenges as humans move farther from Earth. We’re managing these challenges by developing and demonstrating capabilities in incremental steps:
Earth Reliant
Earth Reliant exploration is focused on research aboard the International Space Station. From this world-class microgravity laboratory, we are testing technologies and advancing human health and performance research that will enable deep space, long duration missions.
On the space station, we are advancing human health and behavioral research for Mars-class missions. We are pushing the state-of-the-art life support systems, printing 3-D parts and analyzing material handling techniques.
Proving Ground
In the Proving Ground, we will learn to conduct complex operations in a deep space environment that allows crews to return to Earth in a matter of days. Primarily operating in cislunar space (the volume of space around the moon). We will advance and validate the capabilities required for humans to live and work at distances much farther away from our home planet…such as at Mars.
Earth Independent
Earth Independent activities build on what we learn on the space station and in deep space to enable human missions to the Mars vicinity, possibly to low-Mars orbit or one of the Martian moons, and eventually the Martian surface. Future Mars missions will represent a collaborative effort between us and our partners.
Did you know….that through our robotic missions, we have already been on and around Mars for 40 years! Taking nearly every opportunity to send orbiters, landers and rovers with increasingly complex experiments and sensing systems. These orbiters and rovers have returned vital data about the Martian environment, helping us understand what challenges we may face and resources we may encounter.
Through the Asteroid Redirect Mission (ARM), we will demonstrate an advanced solar electric propulsion capability that will be a critical component of our journey to Mars. ARM will also provide an unprecedented opportunity for us to validate new spacewalk and sample handling techniques as astronauts investigate several tons of an asteroid boulder.
Living and working in space require accepting risks – and the journey to Mars is worth the risks. A new and powerful space transportation system is key to the journey, but we will also need to learn new ways of operating in space.
We Need You!
In the future, Mars will need all kinds of explorers, farmers, surveyors, teachers…but most of all YOU! As we overcome the challenges associated with traveling to deep space, we will still need the next generation of explorers to join us on this journey. Come with us on the journey to Mars as we explore with robots and send humans there one day.
We’re offering a behind-the-scenes look Thursday, Aug. 18 at our journey to Mars. Join us for the following events:
Journey to Mars Televised Event at 9:30 a.m. EDT Join in as we host a conversation about the numerous efforts enabling exploration of the Red Planet. Use #askNASA to ask your questions! Tune in HERE.
Facebook Live at 1:30 p.m. EDT Join in as we showcase the work and exhibits at our Michoud Assembly Facility. Participate HERE.
Hot Fire Test of an RS-25 Engine at 6 p.m. EDT The 7.5-minute test is part of a series of tests designed to put the upgraded former space shuttle engines through the rigorous temperature and pressure conditions they will experience during a launch. Watch HERE.
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Earth and the Moon are in a constant dance as they orbit the Sun — and in June 2020, they’ll create two special celestial events.
Earth has a slight tilt as it orbits the Sun, and June is one of two times each year when that tilt is most prominent: a solstice. At the solstices, which happen each year in June and December, Earth’s tilt is at the greatest angle with respect to the plane of its orbit, meaning that one hemisphere is tilted towards the Sun, and the other hemisphere is tilted away.
In the Northern Hemisphere, June 20 is the summer solstice — the Northern Hemisphere is tilted towards the Sun, so the June solstice is the day on which the Northern Hemisphere receives the longest stretch of daylight for the year.
In both hemispheres, the Sun will rise and set at its northernmost point on the horizon. After June 20, the Sun will appear to travel south.
This view from our Earth Polychromatic Imaging Camera on the National Oceanic and Atmospheric Administration's DSCOVR satellite shows the change in Earth’s tilt between the June and December solstices.
During the June solstice, the Southern Hemisphere is tilted away from the Sun, meaning the June solstice marks its shortest stretch of daylight for the year. June is the Southern Hemisphere’s winter solstice.
The day after the solstice will see another special celestial event: an annular eclipse. Eclipses happen when the Moon lines up just right between the Sun and Earth, allowing it to block out part or all of the Sun’s bright face and cast a shadow on Earth. Though the Moon orbits Earth about once a month, its orbit is tilted by five degrees, so the perfect alignment that creates an eclipse is relatively rare. Often the Moon is too high or low in our sky to block out the Sun.
The June 21, 2020, eclipse is an annular eclipse visible primarily in Africa and Asia. During an annular eclipse, the Moon is too far from Earth and its apparent size is too small to entirely block out the face of the Sun, leaving a sliver of the Sun visible around the Moon’s edge during the eclipse and creating a “ring of fire” effect.
Credit: Dale Cruikshank
Outside the path of annularity, people in other parts of Africa, Asia and even some of Europe and the Pacific have a chance to see a partial solar eclipse, weather permitting. The degree of the partial eclipse depends on how close you are to the path of annularity. Locations far from the path of annularity will see only a small part of the Sun covered by the Moon, while places close to the path will see almost all of the Sun obscured.
No matter where you are, you must take safety precautions to watch the eclipse safely. There is no part of an annular eclipse during which it is safe to look directly at the Sun. You must use a proper solar filter or an indirect viewing method during all phases of the eclipse — even if only a tiny sliver of the Sun is visible around the Moon’s edge, that’s still enough to cause damage to your eyes.
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