In 40 Million Years, Mars May Have A Ring (and One Fewer Moon)

Ten interesting facts about Saturn

Saturn is sometimes called “The Jewel of the Solar System.” It is a planet that is nothing like our own. Humans have been gazing up at Saturn for a long time. They have been wondering about it for thousands of years.

Here are some fun facts about the Ringed Planet.

Saturn is huge. It is the second largest planet in our Solar System. Jupiter is the only planet that is bigger.

The rings are huge but thin. The main rings could almost go from Earth to the moon. Yet, they are less than a kilometer thick.

Four spacecraft have visited Saturn: Pioneer 11, Voyager 1 and 2, and the Cassini-Huygens mission have all studied the planet. 

Saturn has oval-shaped storms similar to Jupiter’s: The region around its north pole has a hexagonal-shaped pattern of clouds. Scientists think this may be a wave pattern in the upper clouds. The planet also has a vortex over its south pole that resembles a hurricane-like storm.

Saturn is made mostly of hydrogen and helium: It exists in layers that get denser farther into the planet. Eventually, deep inside, the hydrogen becomes metallic. At the core lies a hot interior. (click the image for a better resolution).

Saturn has 62 moons: Some of these are large, like Titan, the second largest moon in the Solar System. But most are tiny – just a few km across, and they have no official names. In fact, the last few were discovered by NASA’s Cassini orbiter just a few years ago. More will probably be discovered in the coming years.

Saturn orbits the Sun once every 29.4 Earth years: Its slow movement against the backdrop of stars earned it the nickname of “Lubadsagush” from the ancient Assyrians. The name means “oldest of the old”.

In Saturn there is aurora: Photographic composition made by the Hubble Space Telescope showing the occurrence of aurora in the southern hemisphere of Saturn at intervals of two days.The aurora is visible only in the ultraviolet.

Saturn spins on its axis very fast. A day on Saturn is 10 hours and 14 minutes.

You can see Saturn with your own eyes: Saturn appears as one of the 5 planets visible with the unaided eye. If Saturn is in the sky at night, you can head outside and see it. To see the rings and the ball of the planet itself, you’ll want to peer through a telescope. But you can amaze your friends and family by pointing out that bright star in the sky, and let them know they’re looking at Saturn.

sources: nasa.gov, universetoday.com and solarsystem.nasa.gov

The Summer Solstice Has Arrived!

This year’s summer solstice for the northern hemisphere arrives at 11:54 a.m. EDT, meaning today is the longest day of the year! The number of daylight hours varies by latitude, so our headquarters in Washington, D.C. will see 14 hours, 53 minutes, and 51 seconds of daylight. A lot can happen in that time! Let’s find out more.

If you’re spending the day outside, you might be in the path of our Earth Science Satellite Fleet (ESSF)! The fleet, made up of over a dozen Earth observation satellites, will pass over the continental United States about 37 times during today’s daylight hours. 

These missions collect data on atmospheric chemistry and composition, cloud cover, ocean levels, climate, ecosystem dynamics, precipitation, and glacial movement, among other things. They aim to do everything from predicting extreme weather to helping informing the public and decision makers with the environment through GPS and imaging. Today, their sensors will send back over 200 gigabytes (GB) of data back to the ground by sunset. 

As the sun sets today, the International Space Station (ISS) will be completing its 10th orbit since sunrise. In that time, a little more than 1 terabyte-worth of data will be downlinked to Earth.

That number encompasses data from ground communications, payloads, experiments, and control and navigation signals for the station. Approximately 330 GB of that TB is video, including live broadcasts and downlinks with news outlets. But as recently-returned astronaut Serena Auñón-Chancellor likes to point out, there’s still room for fun. The astronauts aboard the ISS can request YouTube videos or movies for what she likes to call “family movie night.”

Astronauts aboard the station also send back images—LOTS of them. Last year, astronauts sent back an average of 66,912 images per month! During today’s long hours of daylight, we expect the crew to send back about 656 images. But with Expedition 59 astronauts David Saint-Jacques (CSA), Anne McClain (NASA), and Oleg Kononenko (RKA) hard at work preparing to return to Earth on Monday, that number might be a little less. 

Say you’re feeling left out after seeing the family dinners and want to join the crew. Would you have enough daylight to travel to the ISS and back on the longest day of the year? Yes, but only if you’re speedy enough, and plan your launch just right. With the current fastest launch-to-docking time of about six hours, you could complete two-and-a-half flights to the ISS today between sunrise and sunset.

When returning from orbit, it’s a longer ordeal. After the Expedition 59 trio arrives on Earth Monday night, they’ll have to travel from Kazakhstan to Houston to begin their post-flight activities. Their journey should take about 18 hours and 30 minutes, just a few hours longer than the hours of daylight we’ll see today.

Happy solstice! Make sure to tune in with us on Monday night for live coverage of the return of Expedition 59. Until then, enjoy the longest day of the year!

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com. 

How Big is Our Galaxy, the Milky Way?

When we talk about the enormity of the cosmos, it’s easy to toss out big numbers – but far harder to wrap our minds around just how large, how far and how numerous celestial bodies like exoplanets – planets beyond our solar system – really are.

So. How big is our Milky Way Galaxy?

We use light-time to measure the vast distances of space.

It’s the distance that light travels in a specific period of time. Also: LIGHT IS FAST, nothing travels faster than light.

How far can light travel in one second? 186,000 miles. It might look even faster in metric: 300,000 kilometers in one second. See? FAST.

How far can light travel in one minute? 11,160,000 miles. We’re moving now! Light could go around the Earth a bit more than 448 times in one minute.

Speaking of Earth, how long does it take light from the Sun to reach our planet? 8.3 minutes. (It takes 43.2 minutes for sunlight to reach Jupiter, about 484 million miles away.) Light is fast, but the distances are VAST.

In an hour, light can travel 671 million miles. We’re still light-years from the nearest exoplanet, by the way. Proxima Centauri b is 4.2 light-years away. So… how far is a light-year? 5.8 TRILLION MILES.

A trip at light speed to the very edge of our solar system – the farthest reaches of the Oort Cloud, a collection of dormant comets way, WAY out there – would take about 1.87 years.

Our galaxy contains 100 to 400 billion stars and is about 100,000 light-years across!

One of the most distant exoplanets known to us in the Milky Way is Kepler-443b. Traveling at light speed, it would take 3,000 years to get there. Or 28 billion years, going 60 mph. So, you know, far.

SPACE IS BIG.

Read more here: go.nasa.gov/2FTyhgH

Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com.

What is Gravitational Lensing?

A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer, that is capable of bending the light from the source as the light travels towards the observer. This effect is known as gravitational lensing, and the amount of bending is one of the predictions of Albert Einstein’s general theory of relativity.

This illustration shows how gravitational lensing works. The gravity of a large galaxy cluster is so strong, it bends, brightens and distorts the light of distant galaxies behind it. The scale has been greatly exaggerated; in reality, the distant galaxy is much further away and much smaller. Credit: NASA, ESA, L. Calcada

There are three classes of gravitational lensing:

1° Strong lensing: where there are easily visible distortions such as the formation of Einstein rings, arcs, and multiple images.

Einstein ring. credit: NASA/ESA&Hubble

2° Weak lensing: where the distortions of background sources are much smaller and can only be detected by analyzing large numbers of sources in a statistical way to find coherent distortions of only a few percent. The lensing shows up statistically as a preferred stretching of the background objects perpendicular to the direction to the centre of the lens. By measuring the shapes and orientations of large numbers of distant galaxies, their orientations can be averaged to measure the shear of the lensing field in any region. This, in turn, can be used to reconstruct the mass distribution in the area: in particular, the background distribution of dark matter can be reconstructed. Since galaxies are intrinsically elliptical and the weak gravitational lensing signal is small, a very large number of galaxies must be used in these surveys.

The effects of foreground galaxy cluster mass on background galaxy shapes. The upper left panel shows (projected onto the plane of the sky) the shapes of cluster members (in yellow) and background galaxies (in white), ignoring the effects of weak lensing. The lower right panel shows this same scenario, but includes the effects of lensing. The middle panel shows a 3-d representation of the positions of cluster and source galaxies, relative to the observer. Note that the background galaxies appear stretched tangentially around the cluster.

3° Microlensing: where no distortion in shape can be seen but the amount of light received from a background object changes in time. The lensing object may be stars in the Milky Way in one typical case, with the background source being stars in a remote galaxy, or, in another case, an even more distant quasar. The effect is small, such that (in the case of strong lensing) even a galaxy with a mass more than 100 billion times that of the Sun will produce multiple images separated by only a few arcseconds. Galaxy clusters can produce separations of several arcminutes. In both cases the galaxies and sources are quite distant, many hundreds of megaparsecs away from our Galaxy.

Gravitational lenses act equally on all kinds of electromagnetic radiation, not just visible light. Weak lensing effects are being studied for the cosmic microwave background as well as galaxy surveys. Strong lenses have been observed in radio and x-ray regimes as well. If a strong lens produces multiple images, there will be a relative time delay between two paths: that is, in one image the lensed object will be observed before the other image.

As an exoplanet passes in front of a more distant star, its gravity causes the trajectory of the starlight to bend, and in some cases results in a brief brightening of the background star as seen by a telescope. The artistic concept illustrates this effect. This phenomenon of gravitational microlensing enables scientists to search for exoplanets that are too distant and dark to detect any other way.Credits: NASA Ames/JPL-Caltech/T. Pyle

Explanation in terms of space–time curvature

Simulated gravitational lensing by black hole by: Earther

In general relativity, light follows the curvature of spacetime, hence when light passes around a massive object, it is bent. This means that the light from an object on the other side will be bent towards an observer’s eye, just like an ordinary lens. In General Relativity the speed of light depends on the gravitational potential (aka the metric) and this bending can be viewed as a consequence of the light traveling along a gradient in light speed. Light rays are the boundary between the future, the spacelike, and the past regions. The gravitational attraction can be viewed as the motion of undisturbed objects in a background curved geometry or alternatively as the response of objects to a force in a flat geometry.

A galaxy perfectly aligned with a supernova (supernova PS1-10afx) acts as a cosmic magnifying glass, making it appear 100 billion times more dazzling than our Sun. Image credit: Anupreeta More/Kavli IPMU.

To learn more, click here. 

(Source)

A high-definition video camera outside the space station captured stark and sobering views of Hurricane Florence, a Category 4 storm. Image Credit: ESA/NASA–A. Gerst

The scene is a late-spring afternoon in the Amazonis Planitia region of northern Mars. The view covers an area about four-tenths of a mile (644 meters) across. North is toward the top. The length of the dusty whirlwind’s shadow indicates that the dust plume reaches more than half a mile (800 meters) in height. The plume is about 30 yards or meters in diameter. Image credit: NASA/JPL-Caltech/Univ. of Arizona

A false-color image of the Great Red Spot of Jupiterfrom Voyager 1. The white oval storm directly below the Great Red Spot has the approximate diameter of Earth. NASA, Caltech/JPL

The huge storm (great white spot) churning through the atmosphere in Saturn’s northern hemisphere overtakes itself as it encircles the planet in this true-color view from NASA’s Cassini spacecraft. Credit: Cassini Imaging Team, SSI, JPL, ESA, NASA; Color Composite: Jean-Luc Dauvergne

The spinning vortex of Saturn’s north polar storm resembles a deep red rose of giant proportions surrounded by green foliage in this false-color image from NASA’s Cassini spacecraft. Measurements have sized the eye at 1,250 miles (2,000 kilometers) across with cloud speeds as fast as 330 miles per hour (150 meters per second). This image is among the first sunlit views of Saturn’s north pole captured by Cassini’s imaging cameras. Credit: NASA/JPL-Caltech/SSI

Colorized infrared image of Uranus obtained on August 6, 2014, with adaptive optics on the 10-meter Keck telescope; white spots are large storms. Image credit: Imke de Pater, University of California, Berkeley / Keck Observatory images.

Neptune’s Great Dark Spot, a large anticyclonic storm similar to Jupiter’s Great Red Spot, observed by NASA’s Voyager 2 spacecraft in 1989. Credit: NASA / Jet Propulsion Lab

This true color image captured by NASA’S Cassini spacecraft before a distant flyby of Saturn’s moon Titan on June 27, 2012, shows a south polar vortex, or a swirling mass of gas around the pole in the atmosphere. Image credit: NASA/JPL-Caltech/Space Science Institute

This artist’s concept shows what the weather might look like on cool star-like bodies known as brown dwarfs. These giant balls of gas start out life like stars, but lack the mass to sustain nuclear fusion at their cores, and instead, fade and cool with time.

New research from NASA’s Spitzer Space Telescope suggests that most brown dwarfs are racked with colossal storms akin to Jupiter’s famous “Great Red Spot.” These storms may be marked by fierce winds, and possibly lightning. The turbulent clouds might also rain down molten iron, hot sand or salts – materials thought to make up the cloud layers of brown dwarfs.

Image credit: NASA/JPL-Caltech/University of Western Ontario/Stony Brook University

In this image, the nightmare world of HD 189733 b is the killer you never see coming. To the human eye, this far-off planet looks bright blue. But any space traveler confusing it with the friendly skies of Earth would be badly mistaken. The weather on this world is deadly. Its winds blow up to 5,400 mph (2 km/s) at seven times the speed of sound, whipping all would-be travelers in a sickening spiral around the planet. And getting caught in the rain on this planet is more than an inconvenience; it’s death by a thousand cuts. This scorching alien world possibly rains glass—sideways—in its howling winds. The cobalt blue color comes not from the reflection of a tropical ocean, as on Earth, but rather a hazy, blow-torched atmosphere containing high clouds laced with silicate particles. Image Credit: ESO/M. Kornmesser

The heliosphere is the bubble-like region of space dominated by the Sun, which extends far beyond the orbit of Pluto. Plasma “blown” out from the Sun, known as the solar wind, creates and maintains this bubble against the outside pressure of the interstellar medium, the hydrogen and helium gas that permeates the Milky Way Galaxy. The solar wind flows outward from the Sun until encountering the termination shock, where motion slows abruptly. The Voyager spacecraft have explored the outer reaches of the heliosphere, passing through the shock and entering the heliosheath, a transitional region which is in turn bounded by the outermost edge of the heliosphere, called the heliopause. The shape of the heliosphere is controlled by the interstellar medium through which it is traveling, as well as the Sun and is not perfectly spherical. The limited data available and unexplored nature of these structures have resulted in many theories. The word “heliosphere” is said to have been coined by Alexander J. Dessler, who is credited with first use of the word in the scientific literature.

On September 12, 2013, NASA announced that Voyager 1 left the heliopause on August 25, 2012, when it measured a sudden increase in plasma density of about forty times. Because the heliopause marks one boundary between the Sun’s solar wind and the rest of the galaxy, a spacecraft such as Voyager 1 which has departed the heliosphere, can be said to have reached interstellar space. source

Loving Vincent (2017) dir. Dorota Kobiela, Hugh Welchman

Ask Ethan: Where Is The Center Of The Universe?

“I am wondering how there isn’t a center of the universe and how the cosmic background radiation is [equally] far away everywhere we look. It seems to me that when the universe expands… there should be a place where it started expanding.”

Ah, the old center of the Universe question. If the Big Bang happened a long time ago, and we see galaxies moving away from us faster and faster the farther away they are, then where did the Big Bang happen? Where did the expansion start?

It seems like such a simple question, but it turns out this is the wrong question to be asking. The way space and the expanding Universe works is very different from the picture most of us have in our heads, which is much more like an explosion than like an expansion. Yet there’s a very large suite of evidence that points us away from an explosion.

Instead of asking *where* the Big Bang occurred, we should be asking *when* the Big Bang occurred. It makes a lot more sense when you think about it in those terms. Come and find out why.