Category: planets

Space Telescope Gets to Work

Our latest space telescope,
Transiting Exoplanet Survey Satellite (TESS), launched in April. This
week, planet hunters worldwide received all the data from the first two months
of its planet search. This view, from four cameras on TESS, shows just one
region of Earth’s southern sky.

image

The Transiting Exoplanet Survey Satellite (TESS) captured
this strip of stars and galaxies in the southern sky during one 30-minute
period in August. Created by combining the view from all four of its cameras, TESS
images will be used to discover new exoplanets. Notable features in this swath
include the Large and Small Magellanic Clouds and a globular cluster called NGC
104. The brightest stars, Beta Gruis and R Doradus, saturated an entire column
of camera detector pixels on the satellite’s second and fourth cameras.

Credit: NASA/MIT/TESS

The data in the images from TESS will soon lead to discoveries of
planets beyond our solar system – exoplanets. (We’re at 3,848 so far!)

image

But first, all that data (about 27 gigabytes a day) needs to be
processed. And where do space telescopes like TESS get their data cleaned up?
At the Star Wash, of course!

image

TESS sends about 10 billion pixels of data to Earth
at a time. A supercomputer at NASA Ames in Silicon Valley processes the raw
data, turning those pixels into measures of a star’s brightness.

image

And that brightness? THAT’S HOW WE FIND PLANETS! A dip in a star’s
brightness can reveal an orbiting exoplanet in transit.

image

TESS will spend a year studying our southern sky, then will turn
and survey our northern sky for another year. Eventually, the space telescope
will observe 85 percent of Earth’s sky, including 200,000 of the brightest and
closest stars to Earth.

image

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

Dark Matter 101: Looking for the missing mass

Here’s the deal — here at NASA we share all
kinds of amazing images of planets,
stars,
galaxies, astronauts,
other humans,
and such, but those photos can only capture part of what’s out there. Every
image only shows ordinary matter (scientists sometimes call it baryonic
matter), which is stuff made from protons, neutrons and electrons. The problem
astronomers have is that most of the
matter in the universe is not ordinary matter – it’s a mysterious substance called dark matter.  

image

What
is dark matter
? We don’t really know.
That’s not to say we don’t know anything about it – we can see its effects on
ordinary matter. We’ve been getting clues about what it is and what it is not
for decades. However, it’s hard to pinpoint its exact nature when it doesn’t
emit light our telescopes can see. 

Misbehaving
galaxies

The first hint that we might be missing
something came in the 1930s when astronomers noticed that the visible matter in
some clusters of galaxies wasn’t enough to hold the cluster together. The
galaxies were moving so fast that they should have gone zinging out of the
cluster before too long (astronomically speaking), leaving no cluster behind.

image

Simulation credit: ESO/L. Calçada

It turns out, there’s a similar problem with individual galaxies.
In the 1960s and 70s, astronomers mapped out how fast the stars in a galaxy
were moving relative to its center. The outer parts of every single spiral
galaxy the scientists looked at were traveling so fast that they should have
been flying apart.

image

Something was missing – a lot of it!

In
order to explain how galaxies moved in clusters and stars moved in individual
galaxies, they needed more matter than scientists could see. And not just a little more matter. A lot … a lot, a lot. Astronomers
call this missing mass “dark matter”
— “dark” because we don’t know
what it is. There would need to be five times as much dark matter as ordinary
matter to solve the problem.  

Holding
things together

Dark matter keeps galaxies and galaxy clusters
from coming apart at the seams, which means dark matter experiences gravity
the same way we do
.

image

In addition to holding things together, it
distorts space like any other mass. Sometimes we see distant
galaxies whose light has been bent around massive objects
on its way
to us. This makes the galaxies appear stretched out or contorted. These distortions provide another measurement of dark
matter
.

Undiscovered
particles?

There have been a number of theories over the
past several decades about what dark matter could be; for example, could dark
matter be black holes and neutron stars – dead stars that aren’t shining anymore?
However, most of the theories have been disproven. Currently, a leading class
of candidates involves an as-yet-undiscovered type of elementary particle
called WIMPs, or Weakly Interacting Massive Particles.

image

Theorists have envisioned a range of WIMP
types and what happens when they collide with each other. Two possibilities are
that the WIMPS could mutually annihilate, or they could produce an
intermediate, quickly decaying particle. In both cases, the collision would end
with the production of gamma rays — the most energetic form of light — within the detection range of our Fermi Gamma-ray Space Telescope.

Tantalizing
evidence close to home

A few years ago, researchers took a look at
Fermi data from near the center of our galaxy and subtracted out the gamma rays
produced by known sources. There was a left-over gamma-ray signal, which could be consistent with some forms of dark matter.

image

While it was an exciting finding, the case is
not yet closed because lots of things at the center of the galaxy make gamma
rays. It’s going to take multiple sightings using other experiments and looking
at other astronomical objects to know
for sure if this excess is from dark matter.

image

In the meantime, Fermi will continue the search, as it has over its 10 years
in space. Learn
more about Fermi and how we’ve been celebrating its first decade in space.

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

Sixty Years of Exploration, Innovation, and Di…

image

Exactly sixty years ago today, we opened our doors for the first time. And since then, we have opened up a universe of discovery and innovation. 

There are so many achievements to celebrate from the past six decades, there’s no way we can go through all of them. If you want to dive deeper into our history of exploration, check out NASA: 60 Years and Counting

In the meantime, take a moonwalk down memory lane with us while we remember a few of our most important accomplishments from the past sixty years!

image

In 1958, President Eisenhower signed the National Aeronautics and Space Act, which effectively created our agency. We officially opened for business on October 1

To learn more about the start of our space program, watch our video: How It All Began. 

image

Alongside the U.S. Air Force, we implemented the X-15 hypersonic aircraft during the 1950s and 1960s to improve aircraft and spacecraft. 

The X-15 is capable of speeds exceeding Mach 6 (4,500 mph) at altitudes of 67 miles, reaching the very edge of space

Dubbed the “finest and most productive research aircraft ever seen,” the X-15 was officially retired on October 24, 1968. The information collected by the X-15 contributed to the development of the Mercury, Gemini, Apollo, and Space Shuttle programs. 

To learn more about how we have revolutionized aeronautics, watch our Leading Edge of Flight video. 

image

On July 20, 1969, Neil Armstrong and Buzz Aldrin became the first humans to walk on the moon. The crew of Apollo 11 had the distinction of completing the first return of soil and rock samples from beyond Earth. 

Astronaut Gene Cernan, during Apollo 17, was the last person to have walked on the surface of the moon. (For now!)

The Lunar Roving Vehicle was a battery-powered rover that the astronauts used during the last three Apollo missions. 

To learn more about other types of technology that we have either invented or improved, watch our video: Trailblazing Technology.

image

Our long-term Earth-observing satellite program began on July 23, 1972 with the launch of Landsat 1, the first in a long series (Landsat 9 is expected to launch in 2020!) We work directly with the U.S. Geological Survey to use Landsat to monitor and manage resources such as food, water, and forests. 

Landsat data is one of many tools that help us observe in immense detail how our planet is changing. From algae blooms to melting glaciers to hurricane flooding, Landsat is there to help us understand our own planet better. 

Off the Earth, for the Earth.

To learn more about how we contribute to the Earth sciences, watch our video: Home, Sweet Home. 

image

Space Transportation System-1, or STS-1, was the first orbital spaceflight of our Space Shuttle program. 

The first orbiter, Columbia, launched on April 12, 1981. Over the next thirty years, Challenger, Discovery, Atlantis, and Endeavour would be added to the space shuttle fleet. 

Together, they flew 135 missions and carried 355 people into space using the first reusable spacecraft.

image

On January 16, 1978, we selected a class of 35 new astronauts–including the first women and African-American astronauts. 

And on June 18, 1983, Sally Ride became the first American woman to enter space on board Challenger for STS-7. 

To learn more about our astronauts, then and now, watch our Humans in Space video.

image

Everybody loves Hubble! The Hubble Space Telescope was launched into orbit on April 24, 1990, and has been blowing our minds ever since. 

Hubble has not only captured stunning views of our distant stars and galaxies, but has also been there for once-in-a-lifetime cosmic events. For example, on January 6, 2010, Hubble captured what appeared to be a head-on collision between two asteroids–something no one has ever seen before.

In this image, Hubble captures the Carina Nebula illuminating a three-light-year tall pillar of gas and dust. 

To learn more about how we have contributed to our understanding of the solar system and beyond, watch our video: What’s Out There?

image

Cooperation to build the International Space Station began in 1993 between the United States, Russia, Japan, and Canada. 

The dream was fully realized on November 2, 2000, when Expedition 1 crew members boarded the station, signifying humanity’s permanent presence in space!

Although the orbiting lab was only a couple of modules then, it has grown tremendously since then! 

To learn more about what’s happening on the orbiting outpost today, visit the Space Station page.

image

We have satellites in the sky, humans in orbit, and rovers on Mars. Very soon, we will be returning humankind to the Moon, and using it as a platform to travel to Mars and beyond.

And most importantly, we bring the universe to you

What are your favorite NASA moments? We were only able to share a few of ours here, but if you want to learn about more important NASA milestones, check out 60 Moments in NASA History or our video, 60 Years in 60 Seconds

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

NASA’s 60th Anniversary: What’s Out ThereIn th…

NASA’s 60th Anniversary: What’s Out There

In the past 60 years, we’ve advanced our understanding of our solar system and beyond. We continually ask “What’s out there?” as we advance humankind and send spacecraft to explore.
Since opening for business on Oct. 1, 1958, our history tells a story of exploration, innovation and discoveries. The next 60 years, that story continues. Learn more: https://www.nasa.gov/60

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

Studying Sediments in Space

An International
Space Station
investigation called BCAT-CS studies dynamic forces between
sediment particles that cluster together.

image

For the study, scientists sent mixtures of quartz and clay particles to the space
station and subjected them to various levels of simulated gravity.

image

Conducting the experiment in microgravity makes it possible to separate out different forces that act on sediments and look at the function of
each.

image

Sediment systems of quartz and clay occur many places on Earth, including rivers,
lakes, and oceans, and affect many
activities,
from deep-sea hydrocarbon drilling to carbon sequestration.

image

Understanding how
sediments behave
has a range of applications on Earth, including predicting and mitigating erosion, improving water
treatment, modeling the carbon cycle,
sequestering contaminants and more accurately finding deep sea oil
reservoirs.

image

It also may provide insight for future studies of the
geology of new and unexplored planets.

image

Follow @ISS_RESEARCH to
learn more.

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

10 Things: Why Cassini Mattered

One year ago, on Sept. 15, 2017, NASA’s Cassini spacecraft ended
its epic exploration of Saturn with a planned dive into the planet’s
atmosphere–sending back new science to the last second. The spacecraft is
gone, but the science continues. Here are 10 reasons why Cassini mattered…

image

1.
Game Changers

Cassini and ESA (European Space Agency)’s Huygens probe expanded our understanding of the
kinds of worlds where life might exist.

image

2. A (Little) Like Home

At Saturn’s largest moon,
Titan, Cassini and Huygens showed us one of the most Earth-like worlds we’ve
ever encountered, with weather, climate and geology that provide new ways to
understand our home planet.

image

3. A Time Machine (In a Sense)

Cassini gave us a portal to see the physical processes that likely
shaped the development of our solar system, as well as planetary systems around
other stars.

image

4. The Long Run

The length of Cassini’s mission enabled us to observe weather and
seasonal changes over nearly half of a Saturn year, improving our understanding
of similar processes at Earth, and potentially those at planets around other
stars.

image

5. Big Science in Small Places

Cassini revealed Saturn’s moons to be unique worlds with their own
stories to tell.

image

6. Ringscape

Cassini showed us the complexity of Saturn’s rings and the
dramatic processes operating within them.

image

7. Pure Exploration

Some of Cassini’s best discoveries were serendipitous. What
Cassini found at Saturn prompted scientists to rethink their understanding of
the solar system.

image

8. The Right Tools for the Job

Cassini represented a staggering achievement of human and
technical complexity, finding innovative ways to use the spacecraft and its
instruments, and paving the way for future missions to explore our solar
system.

image

9. Jewel of the Solar System

Cassini revealed the beauty of Saturn, its rings and moons,
inspiring our sense of wonder and enriching our sense of place in the cosmos.

image

10. Much Still to Teach Us

The data returned by Cassini during its 13 years at Saturn will
continue to be studied for decades, and many new discoveries are undoubtedly
waiting to be revealed. To keep pace with what’s to come, we’ve created a new
home for the mission–and its spectacular images–at https://solarsystem.nasa.gov/cassini.

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

NASA’s New Planet Hunter Reveals a Sky Full of…

image

NASA’s newest planet-hunting satellite — the Transiting
Exoplanet Survey Satellite, or TESS for short
— has just released its first science image using all
of its cameras to capture a huge swath of the sky! TESS is NASA’s next step in the
search for planets outside our solar system, called exoplanets.

image

This spectacular image, the first released
using all four of TESS’ cameras, shows the satellite’s full field of view. It
captures parts of a dozen constellations, from Capricornus
(the Sea Goat) to Pictor
(the Painter’s Easel) — though it might be hard to find familiar constellations
among all these stars! The image even includes the Large and Small Magellanic
Clouds, our galaxy’s two largest companion galaxies.

The science community calls this image “first
light,” but don’t let that fool you — TESS has been seeing light since it
launched in April. A first light image like this is released to show off the
first science-quality image taken after a mission starts collecting science
data, highlighting a spacecraft’s capabilities.

image

TESS has been busy since it launched from NASA’s Kennedy Space Center in Cape Canaveral, Florida. First TESS needed to get into position, which required a push from the Moon.

After nearly a month in space, the satellite
passed about 5,000 miles from the Moon, whose gravity gave it the boost it needed to get into a special orbit
that will keep it stable and maximize its view of the sky.

image

During those first few weeks, we also got a
sneak peek of the sky through one of TESS’s four cameras. This test image
captured over 200,000 stars in just two seconds! The spacecraft was pointed
toward the constellation Centaurus when it snapped this picture. The bright
star Beta
Centauri
is visible at the lower left edge, and the edge
of the Coalsack
Nebula
is in the right upper corner.

image

After settling into orbit, scientists ran a
number of checks on TESS, including testing its ability to collect a set of
stable images over a prolonged period of time. TESS not only proved its ability
to perform this task, it also got a surprise! A comet named C/2018 N1 passed through TESS’s cameras
for about 17 hours in July.

The images show a treasure
trove of cosmic curiosities
. There are some stars whose
brightness changes over time and asteroids visible as small moving white dots.
You can even see an arc of stray light from Mars, which is located outside the
image, moving across the screen.

image

Now that TESS has settled into orbit and has
been thoroughly tested, it’s digging into its main mission of finding planets around other stars.
How will it spot something as tiny and faint as a planet trillions of miles
away? The trick is to look at the star!

So far, most
of the exoplanets we’ve found
were detected by looking
for tiny dips in the brightness of their host stars. These dips are caused by
the planet passing between us and its star – an event called a transit. Over
its first two years, TESS will stare at 200,000 of the nearest and brightest stars
in the sky to look for transits to identify stars with planets.

image

TESS will be building on the legacy of NASA’s Kepler spacecraft, which also used
transits to find exoplanets. TESS’s target stars are about 10 times closer than
Kepler’s, so they’ll tend to be brighter. Because they’re closer and brighter,
TESS’s target stars will be ideal candidates for follow-up studies with current
and future observatories.

image

TESS is challenging over 200,000 of our
stellar neighbors to a staring contest! Who knows what new amazing planets
we’ll find?

The
TESS mission is led by MIT
and came together with the help of many
different partners
. You can keep up
with the latest from the TESS mission by following mission updates.

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

What’s Up For September 2018?

Outstanding views Venus, Jupiter, Saturn and Mars with the naked eye!

image

You’ll have to look quickly after sunset to catch Venus. And through binoculars or a telescope, you’ll see Venus’s phase change dramatically during September – from nearly half phase to a larger thinner crescent!

image

Jupiter, Saturn and Mars continue their brilliant appearances this month. Look southwest after sunset.

image

Use the summer constellations help you trace the Milky Way.

image

Sagittarius: where stars and some brighter clumps appear as steam from the teapot.

image

Aquila: where the Eagle’s bright Star Altair, combined with Cygnus’s Deneb, and Lyra’s Vega mark the Summer Triangle. 

image

Cassiopeia, the familiar “w”- shaped constellation completes the constellation trail through the Summer Milky Way. Binoculars will reveal double stars, clusters and nebulae. 

image

Between September 12th and the 20th, watch the Moon pass from near Venus, above Jupiter, to the left of Saturn and finally above Mars! 

image

Both Neptune and brighter Uranus can be spotted with some help from a telescope this month.

Look at about 1:00 a.m. local time or later in the southeastern sky. You can find Mercury just above Earth’s eastern horizon shortly before sunrise. Use the Moon as your guide on September 7 and 8th.

And although there are no major meteor showers in September, cometary dust appears in another late summer sight, the morning Zodiacal light. Try looking for it in the east on moonless mornings very close to sunrise. To learn more about the Zodiacal light, watch “What’s Up” from March 2018.

Watch the full What’s Up for September Video: 

There are so many sights to see in the sky. To stay informed, subscribe to our What’s Up video series on Facebook.

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

Why Bennu? 10 Reasons

After traveling for two years and billions of kilometers from Earth, the OSIRIS-REx probe is only a few months away from its destination: the intriguing asteroid Bennu. When it arrives in December, OSIRIS-REx will embark on a nearly two-year investigation of this clump of rock, mapping its terrain and finding a safe and fruitful site from which to collect a sample.

The spacecraft will briefly touch Bennu’s surface around July 2020 to collect at least 60 grams (equal to about 30 sugar packets) of dirt and rocks. It might collect as much as 2,000 grams, which would be the largest sample by far gathered from a space object since the Apollo Moon landings. The spacecraft will then pack the sample into a capsule and travel back to Earth, dropping the capsule into Utah’s west desert in 2023, where scientists will be waiting to collect it.

This years-long quest for knowledge thrusts Bennu into the center of one of the most ambitious space missions ever attempted. But the humble rock is but one of about 780,000 known asteroids in our solar system. So why did scientists pick Bennu for this momentous investigation? Here are 10 reasons:

1. It’s close to Earth

image

Unlike most other asteroids that circle the Sun in the asteroid belt between Mars and Jupiter, Bennu’s orbit is close in proximity to Earth’s, even crossing it. The asteroid makes its closest approach to Earth every 6 years. It also circles the Sun nearly in the same plane as Earth, which made it somewhat easier to achieve the high-energy task of launching the spacecraft out of Earth’s plane and into Bennu’s. Still, the launch required considerable power, so OSIRIS-REx used Earth’s gravity to boost itself into Bennu’s orbital plane when it passed our planet in September 2017.

2. It’s the right size

image

Asteroids spin on their axes just like Earth does. Small ones, with diameters of 200 meters or less, often spin very fast, up to a few revolutions per minute. This rapid spinning makes it difficult for a spacecraft to match an asteroid’s velocity in order to touch down and collect samples. Even worse, the quick spinning has flung loose rocks and soil, material known as “regolith” — the stuff OSIRIS-REx is looking to collect — off the surfaces of small asteroids. Bennu’s size, in contrast, makes it approachable and rich in regolith. It has a diameter of 492 meters, which is a bit larger than the height of the Empire State Building in New York City, and rotating once every 4.3 hours.

3. It’s really old

image

Bennu is a leftover fragment from the tumultuous formation of the solar system. Some of the mineral fragments inside Bennu could be older than the solar system. These microscopic grains of dust could be the same ones that spewed from dying stars and eventually coalesced to make the Sun and its planets nearly 4.6 billion years ago. But pieces of asteroids, called meteorites, have been falling to Earth’s surface since the planet formed. So why don’t scientists just study those old space rocks? Because astronomers can’t tell (with very few exceptions) what kind of objects these meteorites came from, which is important context. Furthermore, these stones, that survive the violent, fiery decent to our planet’s surface, get contaminated when they land in the dirt, sand, or snow. Some even get hammered by the elements, like rain and snow, for hundreds or thousands of years. Such events change the chemistry of meteorites, obscuring their ancient records.

4. It’s well preserved

image

Bennu, on the other hand, is a time capsule from the early solar system, having been preserved in the vacuum of space. Although scientists think it broke off a larger asteroid in the asteroid belt in a catastrophic collision between about 1 and 2 billion years ago, and hurtled through space until it got locked into an orbit near Earth’s, they don’t expect that these events significantly altered it.

5. It might contain clues to the origin of life

image

Analyzing a sample from Bennu will help planetary scientists better understand the role asteroids may have played in delivering life-forming compounds to Earth. We know from having studied Bennu through Earth- and space-based telescopes that it is a carbonaceous, or carbon-rich, asteroid. Carbon is the hinge upon which organic molecules hang. Bennu is likely rich in organic molecules, which are made of chains of carbon bonded with atoms of oxygen, hydrogen, and other elements in a chemical recipe that makes all known living things. Besides carbon, Bennu also might have another component important to life: water, which is trapped in the minerals that make up the asteroid.

6. It contains valuable materials

image

Besides teaching us about our cosmic past, exploring Bennu close-up will help humans plan for the future. Asteroids are rich in natural resources, such as iron and aluminum, and precious metals, such as platinum. For this reason, some companies, and even countries, are building technologies that will one day allow us to extract those materials. More importantly, asteroids like Bennu are key to future, deep-space travel. If humans can learn how to extract the abundant hydrogen and oxygen from the water locked up in an asteroid’s minerals, they could make rocket fuel. Thus, asteroids could one day serve as fuel stations for robotic or human missions to Mars and beyond. Learning how to maneuver around an object like Bennu, and about its chemical and physical properties, will help future prospectors.

7. It will help us better understand other asteroids

image

Astronomers have studied Bennu from Earth since it was discovered in 1999. As a result, they think they know a lot about the asteroid’s physical and chemical properties. Their knowledge is based not only on looking at the asteroid, but also studying meteorites found on Earth, and filling in gaps in observable knowledge with predictions derived from theoretical models. Thanks to the detailed information that will be gleaned from OSIRIS-REx, scientists now will be able to check whether their predictions about Bennu are correct. This work will help verify or refine telescopic observations and models that attempt to reveal the nature of other asteroids in our solar system.

8. It will help us better understand a quirky solar force …

image

Astronomers have calculated that Bennu’s orbit has drifted about 280 meters (0.18 miles) per year toward the Sun since it was discovered. This could be because of a phenomenon called the Yarkovsky effect, a process whereby sunlight warms one side of a small, dark asteroid and then radiates as heat off the asteroid as it rotates. The heat energy thrusts an asteroid either away from the Sun, if it has a prograde spin like Earth, which means it spins in the same direction as its orbit, or toward the Sun in the case of Bennu, which spins in the opposite direction of its orbit. OSIRIS-REx will measure the Yarkovsky effect from close-up to help scientists predict the movement of Bennu and other asteroids. Already, measurements of how this force impacted Bennu over time have revealed that it likely pushed it to our corner of the solar system from the asteroid belt.

9. … and to keep asteroids at bay

image

One reason scientists are eager to predict the directions asteroids are drifting is to know when they’re coming too-close-for-comfort to Earth. By taking the Yarkovsky effect into account, they’ve estimated that Bennu could pass closer to Earth than the Moon is in 2135, and possibly even closer between 2175 and 2195. Although Bennu is unlikely to hit Earth at that time, our descendants can use the data from OSIRIS-REx to determine how best to deflect any threatening asteroids that are found, perhaps even by using the Yarkovsky effect to their advantage.

10. It’s a gift that will keep on giving

Samples of Bennu will return to Earth on September 24, 2023. OSIRIS-REx scientists will study a quarter of the regolith. The rest will be made available to scientists around the globe, and also saved for those not yet born, using techniques not yet invented, to answer questions not yet asked.

Read the web version of this week’s “Solar System: 10 Things to Know” article HERE.

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

Solar System 10 Things: Dust in the Wind, on M…

To most of us, dust is an annoyance. Something to be cleaned up, washed off or wiped away. But these tiny particles that float about and settle on surfaces play an important role in a variety of processes on Earth and across the solar system. So put away that feather duster for a few moments, as we share with you 10 things to know about dust.

image

1. “Dust” Doesn’t Mean Dirty, it Means Tiny

Not all of what we call “dust” is made of the same stuff. Dust in your home generally consists of things like particles of sand and soil, pollen, dander (dead skin cells), pet hair, furniture fibers and cosmetics. But in space, dust can refer to any sort of fine particles smaller than a grain of sand. Dust is most commonly bits of rock or carbon-rich, soot-like grains, but in the outer solar system, far from the Sun’s warmth, it’s also common to find tiny grains of ice as well. Galaxies, including our Milky Way, contain giant clouds of fine dust that are light years across – the ingredients for future generations of planetary systems like ours.

image

2. Some Are Big, Some Are Small (and Big Ones Tend to Fall)

Dust grains come in a range of sizes, which affects their properties. Particles can be extremely tiny, from only a few tens of nanometers (mere billionths of a meter) wide, to nearly a millimeter wide. As you might expect, smaller dust grains are more easily lifted and pushed around, be it by winds or magnetic, electrical and gravitational forces. Even the gentle pressure of sunlight is enough to move smaller dust particles in space. Bigger particles tend to be heavier, and they settle out more easily under the influence of gravity.

For example, on Earth, powerful winds can whip up large amounts of dust into the atmosphere. While the smaller grains can be transported over great distances, the heavier particles generally sink back to the ground near their source. On Saturn’s moon Enceladus, jets of icy dust particles spray hundreds of miles up from the surface; the bigger particles are lofted only a few tens of miles (or kilometers) and fall back to the ground, while the finest particles escape the moon’s gravity and go into orbit around Saturn to create the planet’s E ring.

image

3. It’s EVERYWHERE

Generally speaking, the space between the planets is pretty empty, but not completely so. Particles cast off by comets and ground up bits of asteroids are found throughout the solar system. Take any volume of space half a mile (1 kilometer) on a side, and you’d average a few micron-sized particles (grains the thickness of a red blood cell).

Dust in the solar system was a lot more abundant in the past. There was a huge amount of it present as the planets began to coalesce out of the disk of material that formed the Sun. In fact, motes of dust gently sticking together were likely some of the earliest seeds of the planet-building process. But where did all that dust come from, originally? Some of it comes from stars like our Sun, which blow off their outer layers in their later years. But lots of it also comes from exploding stars, which blast huge amounts of dust and gas into space when they go boom.

image

4. From a Certain Point of View

Dust is easier to see from certain viewing angles. Tiny particles scatter light depending on how big their grains are. Larger particles tend to scatter light back in the direction from which it came, while very tiny particles tend to scatter light forward, more or less in the direction it was already going. Because of this property, structures like planetary rings made of the finest dusty particles are best viewed with the Sun illuminating them from behind. For example, Jupiter’s rings were only discovered after the Voyager 1 spacecraft passed by the planet, where it could look back and see them backlit by the Sun. You can see the same effect looking through a dusty windshield at sunset; when you face toward the Sun, the dust becomes much more apparent.

image

5. Dust Storms Are Common on Mars

Local dust storms occur frequently on Mars, and occasionally grow or merge to form regional systems, particularly during the southern spring and summer, when Mars is closest to the Sun. On rare occasions, regional storms produce a dust haze that encircles the planet and obscures surface features beneath. A few of these events may become truly global storms, such as one in 1971 that greeted the first spacecraft to orbit Mars, our Mariner 9. In mid-2018, a global dust storm enshrouded Mars, hiding much of the Red Planet’s surface from view and threatening the continued operation of our uber long-lived Opportunity rover. We’ve also seen global dust storms in 1977, 1982, 1994, 2001 and 2007.

Dust storms will likely present challenges for future astronauts on the Red Planet. Although the force of the wind on Mars is not as strong as portrayed in an early scene in the movie “The Martian,” dust lofted during storms could affect electronics and health, as well as the availability of solar energy.

6. Dust From the Sahara Goes Global

Earth’s largest, hottest desert is connected to its largest tropical rain forest by dust. The Sahara Desert is a near-uninterrupted brown band of sand and scrub across the northern third of Africa. The Amazon rain forest is a dense green mass of humid jungle that covers northeast South America. But after strong winds sweep across the Sahara, a dusty cloud rises in the air, stretches between the continents, and ties together the desert and the jungle.

This trans-continental journey of dust is important because of what is in the dust. Specifically, the dust picked up from the Bodélé Depression in Chad – an ancient lake bed where minerals composed of dead microorganisms are loaded with phosphorus. Phosphorus is an essential nutrient for plant proteins and growth, which the nutrient-poor Amazon rain forest depends on in order to flourish.

image

7. Rings and Things

The rings of the giant planets contain a variety of different dusty materials. Jupiter’s rings are made of fine rock dust. Saturn’s rings are mostly pure water ice, with a sprinkling of other materials. (Side note about Saturn’s rings: While most of the particles are boulder-sized, there’s also lots of fine dust, and some of the fainter rings are mostly dust with few or no large particles.) Dust in the rings of Uranus and Neptune is made of dark, sooty material, probably rich in carbon.

Over time, dust gets removed from ring systems due to a variety of processes. For example, some of the dust falls into the planet’s atmosphere, while some gets swept up by the planets’ magnetic fields, and other dust settles onto the surfaces of the moons and other ring particles. Larger particles eventually form new moons or get ground down and mixed with incoming material. This means rings can change a lot over time, so understanding how the tiniest ring particles are being moved about has bearing on the history, origins and future of the rings.

image

8. Moon Dust is Clingy and Might Make You Sick

So, dust is kind of a thing on the Moon. When the Apollo astronauts visited the Moon, they found that lunar dust quickly coated their spacesuits and was difficult to remove. It was quite abrasive, causing wear on their spacesuit fabrics, seals and faceplates. It also clogged mechanisms like the joints in spacesuit limbs, and interfered with fasteners like zippers and Velcro. The astronauts also noted that it had a distinctive, pungent odor, not unlike gunpowder, and it was an eye and lung irritant.

Many of these properties apparently can be explained by the fact that lunar dust particles are quite rough and jagged. While dust particles on Earth get tumbled and ground by the wind into smoother shapes, this sort of weathering doesn’t happen so much on the Moon. The roughness of Moon dust grains makes it very easy for them to cling to surfaces and scratch them up. It also means they’re not the sort of thing you would want to inhale, as their jagged edges could damage delicate tissues in the lung.

image

9. Dust is What Makes Comets So Pretty

Most comets are basically clods of dust, rock and ice. They spend most of their time far from the Sun, out in the refrigerated depths of the outer solar system, where they’re peacefully dormant. But when their orbits carry them closer to the Sun – that is, roughly inside the orbit of Jupiter – comets wake up. In response to warming temperatures, the ices on and near their surfaces begin to turn into gases, expanding outward and away from the comet, and creating focused jets of material in places. Dust gets carried away by this rapidly expanding gas, creating a fuzzy cloud around the comet’s nucleus called a coma. Some of the dust also is drawn out into a long trail – the comet’s tail.

image

10. We’re Not the Only Ones Who’re So Dusty

Dust in our solar system is continually replenished by comets whizzing past the Sun and the occasional asteroid collision, and it’s always being moved about, thanks to a variety of factors like the gravity of the planets and even the pressure of sunlight. Some of it even gets ejected from our solar system altogether.

With telescopes, we also observe dusty debris disks around many other stars. As in our own system, the dust in such disks should evolve over time, settling on planetary surfaces or being ejected, and this means the dust must be replenished in those star systems as well. So studying the dust in our planetary environs can tell us about other systems, and vice versa. Grains of dust from other planetary systems also pass through our neighborhood – a few spacecraft have actually captured and analyzed some them – offering us a tangible way to study material from other stars.

Read the full version of ‘Solar System: 10 Things to Know’ article HERE

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