Tag Archives: planets

Brave New Worlds and Goldilocks

In this photograph, taken by an astronaut on board the International Space Station, Venus is seen moving in front of, or transiting, the sun. Although the planet is small in comparison to the sun, it blocks part of the light reaching the earth. Using very sensitive instruments, scientists can now measure the very slight dimming that occurs when an exoplanet blocks part of the light from a distant star it orbits. (Photo: NASA)
In this photograph, taken by an astronaut on board the International Space Station, Venus is seen moving in front of, or transiting, the sun. Although the planet is small in comparison to the sun, it blocks part of the light reaching the earth. Using very sensitive instruments, scientists can now measure the very slight dimming that occurs when an exoplanet blocks part of the light from a distant star it orbits. (Photo: NASA)
Do we know if there are planets orbiting other stars? Until about 20 years ago, the answer would have been “NO!” Most astronomers believed that there were probably planets going around other stars, but that it was not possible to find them. Planets are just so small compared to stars and the stars are so far away.

Then, in the 1990s, some really smart scientists thought up some crazy ideas to detect planets orbiting distant stars.

The simplest one became known as the Transit Method. When Mercury or Venus travel across the disc of the Sun (known as transiting the Sun), the amount of sunlight hitting the Earth goes down.

Think about a light bulb burning and a fly buzzing around it. While you look at the bulb as the fly buzzes by, the amount of light you see from the bulb is slightly less than when the fly is gone. It’s a very small amount, but the bulb does in fact become dimmer.

Now what if we could measure the brightness of a distant star incredibly accurately, and see if it dims? And what the star dims and brightens on a regular basis (like once a year)?

If that’s the case, it might be caused by a planet orbiting the star.

Let me pause and be the science grammar policeman. Technically, as poor Pluto learned, there are only 8 planets; a planet is now defined as a celestial body that, among other things, orbits our Sun. So if we’re talking about worlds orbiting some other star, they cannot be called planets. Astronomers call them exoplanets. “Exo” means “outside,” so exoplanet means a planet orbiting a star outside our solar system.

Using the Transit Method and other ingenious methods, astronomers started finding exoplanets, lots of them. It takes a long time to be sure. It takes multiple observations by multiple teams using multiple methods before an exoplanet is confirmed.

Now, hundreds of exoplanets have been confirmed. Thousands more listed as probable but haven’t been confirmed yet. The number keeps growing.

The artist's concept depicts NASA's Kepler mission's smallest habitable zone planet. Seen in the foreground is Kepler-62f, a super-Earth-size planet in the habitable zone of a star smaller and cooler than the sun, located about 1,200 light-years from Earth in the constellation Lyra. Kepler-62f orbits it's host star every 267 days and is roughly 40 percent larger than Earth in size. The size of Kepler-62f is known, but its mass and composition are not. However, based on previous exoplanet discoveries of similar size that are rocky, scientists are able to determine its mass by association. Much like our solar system, Kepler-62 is home to two habitable zone worlds. The small shining object seen to the right of Kepler-62f is Kepler-62e. Orbiting on the inner edge of the habitable zone, Kepler-62e is roughly 60 percent larger than Earth. (Image credit: NASA Ames/JPL-Caltech/Tim Pyle)
The artist’s concept depicts NASA’s Kepler mission’s smallest habitable zone planet. Seen in the foreground is Kepler-62f, a super-Earth-size planet in the habitable zone of a star smaller and cooler than the sun, located about 1,200 light-years from Earth in the constellation Lyra. Kepler-62f orbits it’s host star every 267 days and is roughly 40 percent larger than Earth in size. The size of Kepler-62f is known, but its mass and composition are not. However, based on previous exoplanet discoveries of similar size that are rocky, scientists are able to determine its mass by association. Much like our solar system, Kepler-62 is home to two habitable zone worlds. The small shining object seen to the right of Kepler-62f is Kepler-62e. Orbiting on the inner edge of the habitable zone, Kepler-62e is roughly 60 percent larger than Earth. (Image credit: NASA Ames/JPL-Caltech/Tim Pyle)
In 2009, NASA launched the Kepler Space telescope to find stars with exoplanets. It tracked the brightness of over 100,000 stars for over 4 years. It has discovered at least 900 confirmed exoplanets, and has provided scientists with so much data that will take years to completely review.

The Kepler scientist have found lots of weird planets. Huge planets bigger than Jupiter yet closer to their star than Mercury, orbiting every few days! They found planets twice the size of Earth, dubbed “Super Earths” really far away from their stars. They found planets orbiting two stars!

Scientists have even been able to determine all sorts of characteristics about these exoplanets including:

  • How big they are.
  • How long is their year.
  • How far away from their star is their orbit.
  • What chemicals are in their atmosphere

Naturally, astronomers want to locate planets that have the right conditions for life. They are looking for exoplanets that have orbits that means they are not too hot and not too cold, planets that are “just right” for life. They call this the Goldilocks zone. They have many candidates, so who knows what they’ll learn in the future?

The Gemini Planet Imager’s first light image of Beta Pictoris b (Processing by Christian Marois, NRC Canada)
The Gemini Planet Imager’s first light image of Beta Pictoris b (Processing by Christian Marois, NRC Canada)
In just a few years exoplanets have gone from science fiction to science fact. Earlier this year, scientists in Chile used special techniques and even took a photograph of an exoplanet! See below the image of Beta Pictoris b, a planet orbiting the star Beta Pictoris. In the picture below, the light of the star itself is blocked out by a disk so the planet can be seen. It’s great to see science in action.

Keep up with the latest exoplanet discoveries yourself at http://kepler.nasa.gov/Mission/discoveries/

Saturn: Weirdo of the Solar System

This is an artists concept of Cassini during the Saturn Orbit Insertion (SOI) maneuver, just after the main engine has begun firing. The spacecraft is moving out of the plane of the page and to the right (firing to reduce its spacecraft velocity with respect to Saturn) and has just crossed the ring plane. Cassini's close proximity to the planet after the maneuver offers a unique opportunity to observe Saturn and its rings at extremely high resolution. Image Credit: NASA/JPL
This is an artists concept of Cassini during the Saturn Orbit Insertion (SOI) maneuver, just after the main engine has begun firing. The spacecraft is moving out of the plane of the page and to the right (firing to reduce its spacecraft velocity with respect to Saturn) and has just crossed the ring plane. Cassini’s close proximity to the planet after the maneuver offers a unique opportunity to observe Saturn and its rings at extremely high resolution.
Image Credit: NASA/JPL
There is a giant robot circling planet Saturn right now. And this robot is finding weird, amazing things: rainstorms of liquid diamonds, hurricanes bigger than the Earth, ice volcanoes…

But before we get to all that, I should back up a bit and give just a little background on Saturn so you will fully appreciate these new discoveries. Saturn is the sixth planet from the Sun, the farthest planet that can be easily seen without a telescope.

We have always known that Saturn was unusual. Actually, all of the planets were a little unusual to ancient star-gazers. They studied the night sky and saw that almost all the bright dots in the sky moved at the same speed and direction. But they also noticed that five bright dots in the sky moved differently than the stars and constellations. They called these five dots planets (which means wanderer): Mercury, Venus, Mars, Jupiter and Saturn wander among the constellations of the night sky.

Galileo's Drawings of SaturnMore than 500 years ago, in the year 1610, Mr. Galileo found that Saturn was really weird. He was the first person to point a telescope at Saturn and he saw the most incredible sight; Saturn had ears! His drawings looked a bit like Mickey Mouse, with a big circle in the middle and ears poking out on the right and left side.

Another astronomer, Chris Huygens, using a better telescope, found that the “ear” Galileo saw were actually a ring around the planet, just like one you might wear on your finger. Then a guy named Gio Cassini used an even better telescope and could see that the ring was actually multiple rings (at least three) with clear separations between them.

As Saturn advances in its orbit toward equinox and the sun gradually moves northward on the planet, the motion of Saturn's ring shadows and the changing colors of its atmosphere continue to transform the face of Saturn as seen by Cassini. Image Credit: PIA11141 NASA/JPL/Space Science Institute
As Saturn advances in its orbit toward equinox and the sun gradually moves northward on the planet, the motion of Saturn’s ring shadows and the changing colors of its atmosphere continue to transform the face of Saturn as seen by Cassini. Image Credit: PIA11141 NASA/JPL/Space Science Institute
Over the years, we have continued to learn just how weird Saturn is. Saturn has at least 62 moons and dozens of rings. It is the second largest planet, called a “gas giant” which means that it has no rocky surface, it’s all air. Even though it’s huge (760 times bigger than Earth), the gas is really light. If you could put Saturn in a big enough bucket of water, it would float!

Although it is so big, it spins really fast; a day on Saturn is only about 10 hours long. Gas spinning that fast causes tremendously violent storms. Hurricanes larger than whole the Earth rage across Saturn all the time.

Titan's atmosphere makes Saturn's largest moon look like a fuzzy orange ball in this natural color view from the Cassini spacecraft. Titan's north polar hood is visible at the top of the image, and a faint blue haze also can be detected above the south pole at the bottom of this view. (Image Credit: PIA14602 NASA/JPL-Caltech/Space Science Institute)
Titan’s atmosphere makes Saturn’s largest moon look like a fuzzy orange ball in this natural color view from the Cassini spacecraft. Titan’s north polar hood is visible at the top of the image, and a faint blue haze also can be detected above the south pole at the bottom of this view. (Image Credit: PIA14602 NASA/JPL-Caltech/Space Science Institute)
Saturn’s super moon, Titan, is bigger than planet Mercury and has clouds, lakes, rivers and oceans.

By 1990 we had learned a whole lot about Saturn using Earth based instruments (and two very brief flyby missions). But there is just so much you can do from about 1 billion miles away. To learn more, we needed to get up close and personal for an extended time.

In 1997 we launched robot spaceship to do just that. It was named in honor of Mr. Cassini, and carried a smaller robot onboard named after Huygens. Cassini/Huygens was the biggest spaceship NASA had ever built, over 6 tons, big as a school bus. After a six year journey Cassini/Huygens arrived at Saturn and started sending back jaw-dropping details about our sixth planet.

In the next post, I will share some of the secrets of Saturn uncovered by Cassini/Huygens. Be prepared to be amazed!

Fun Phineas Facts
Saturn’s rings disappear every few years! It happened in 1612, completely shocking Galileo. Then to his surprise, the next year they reappeared.

To understand why, you can do a simple experiment. Find a round disc in your home (a quarter, CD, frisbee…) and hold it out at arms length so it looks like a circle. Now tilt it so all you can see is the edge.

Saturns rings are like the disc in your hand. Saturns rings are very wide, but only 30 feet thick. As seen from Earth, Saturns rings wobble, and about every 7 years they are edge on, and basically invisible to us. Then they wobble some more and reappear.

References:

http://www.space.com/48-saturn-the-solar-systems-major-ring-bearer.html

http://saturn.jpl.nasa.gov/

Museo Galileo

Armchair Explorer: Postcards from the Red Planet

mars_rover
Self-Portrait of Mars Rover Curiosity – NASA/JPL-Caltech/MSSS


No matter how far you go, it’s always nice to keep in touch with the folks back home. That’s especially true for a spacecraft that has traveled millions of miles just to send pictures and other information from the surface of Mars back to scientists on Earth.

On June 19, researchers at NASA released their biggest, most detailed picture ever of the surface of Mars. For space fans following the progress of NASA’s Mars rover — named “Curiosity” — as it explores the surface of the Red Planet, pictures are nothing new. One of the great things about NASA is that mission scientists share lots of the data sent back to Earth. Armchair explorers can browse information on the Web — photos, charts, maps, animations and multimedia — alongside scientists around the world.

But the latest picture is NASA’s hugest ever (in camera terms, more than one billion pixels!), which means you can change your viewing angle, move it around and look at different parts of it. When you see something interesting, you can zoom in for closer inspection. See an interesting rock a mile away? No problem. Click and zoom until you get a better look.

It’s as close as you can get to taking a stroll around the surface of Mars.

Billion-Pixel View of Mars Surface with Pan and Zoom

The reason such detail is possible is that the image is made by stitching together nearly 900 pictures taken by Curiosity as it moved around the surface. The pictures were taken over several days in the October and November of 2012. The area photographed includes a windblown patch named “Rocknest,” and extends to Mount Sharp on the horizon. “It gives a sense of place and really shows off the cameras’ capabilities,” said Bob Deen of the Multi-Mission Image Processing Laboratory at NASA’s Jet Propulsion Laboratory, Pasadena, Calif.

To access the image and start your own “roving” adventure, go click on the link above.


TERMS

NASA: National Aeronautics and Space Administration, an independent agency of the United States government responsible for aviation and spaceflight.

PIXEL: The basic unit of the composition of an image on a display screen; basically, one single dot that can’t be divided.


SOURCES

PRESS RELEASE: Billion-Pixel View of Mars Comes From Curiosity Rover

WEB: NASA’s Mars Science Laboratory

WEB: NASA’s All About Mars

WIKI: Mars Science Laboratory

WEB: Information on NASA’s Multi-Mission Image Processing Laboratory


PHOTO CREDIT

Image credit: NASA/JPL-Caltech/MSSS “Updated Curiosity Self-Portrait at ‘John Klein'” This self-portrait of NASA’s Mars rover Curiosity combines dozens of exposures taken by the rover’s Mars Hand Lens Imager (MAHLI) during the 177th Martian day, or sol, of Curiosity’s work on Mars (Feb. 3, 2013), plus three exposures taken during Sol 270 (May 10, 2013) to update the appearance of part of the ground beside the rover. The updated area, which is in the lower left quadrant of the image, shows gray-powder and two holes where Curiosity used its drill on the rock target “John Klein.” The portion has been spliced into a self-portrait that was prepared and released in February (http://photojournal.jpl.nasa.gov/catalog/PIA16764), before the use of the drill. The result shows what the site where the self-portrait was taken looked like by the time the rover was ready to drive away from that site in May 2013.

The rover’s robotic arm is not visible in the mosaic. MAHLI, which took the component images for this mosaic, is mounted on a turret at the end of the arm. Wrist motions and turret rotations on the arm allowed MAHLI to acquire the mosaic’s component images. The arm was positioned out of the shot in the images, or portions of images, used in the mosaic.

Malin Space Science Systems, San Diego, developed, built and operates MAHLI. NASA’s Jet Propulsion Laboratory, Pasadena, Calif., manages the Mars Science Laboratory Project and the mission’s Curiosity rover for NASA’s Science Mission Directorate in Washington. The rover was designed and assembled at JPL, a division of the California Institute of Technology in Pasadena.

What Happened to Planet Pluto?

planet_pluto_facesFor 75 years, kids around the world learned about the nine planets that go around (orbit) the sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto. And then in 2006, Pluto was gone; there were only eight planets! What happened to Pluto?

Pluto was discovered in 1930 by Clyde Tombaugh at the Lowell Observatory in Arizona. And from the beginning we knew that Pluto was weird. It was not like the other eight.

It was usually the farthest planet from the sun, though sometimes it was closer than Neptune. It was tiny, smaller than Earth’s Moon. It wasn’t round either, more like a potato than a ball.

And while the other eight planets orbits are almost circular, Pluto’s orbit was a deep oval (like the shape of an egg). And it has 4 moons, one almost as big as Pluto itself.

None of that bothered space scientists (astronomers) until 2005 when they found a 10th planet, Ceres! Ceres is bigger than Pluto, but just as weird. But just when they were about to update all the textbooks to include #10, they found an 11th, Eris.

Soon astronomers realized that Ceres and Eris were just some of hundreds of objects orbiting way out past Neptune. If Ceres is a planet, then they all are! Imagine having to memorize all of them for a science quiz!

So the scientists changed the definition of “planet.” Definitions are really important in science. They keep everyone in the world talking the same language. So making the change was a big deal.

After much debate, they agreed that to be called a planet, you needed to:

  1. Be nearly round like a ball
  2. Have an orbit close to a circle around the Sun
  3. Have cleared out the neighborhood (orbit) of other floating junk

Pluto, Ceres and all the others did not meet the definition and were officially renamed “Dwarf Planets.”

So, Pluto is still out there, but it is no longer considered a planet. However, it’s still a weird, cool rock. And we are about to learn even more about it In 2015, a NASA rocket arrives at Pluto! The “New Horizons” mission will take the first ever close up look at the most famous dwarf planet.

Fun Phineas Fact: Planet Pluto was named by an 11-year-old girl from England.


SOURCES

WEB: Space.com: Dwarf Planets

WEB: NinePlanets.org

WEB: UniverseToday – Interesting Facts About Pluto

PODCAST: Astronomycast Episode #1


PHOTO CREDIT: NASA, ESA, and M. Buie (Southwest Research Institute): This is the most detailed view to date of the entire surface of the dwarf planet Pluto, as constructed from multiple NASA Hubble Space Telescope photographs taken from 2002 to 2003.