We've been looking at other planets through telescopes for four centuries. But if you really want to get to know a place, there's no substitute for being there. And in the past decade, more than 20 spacecraft have ventured into the deepest reaches of our solar system. These probes, unlike the Hubble Space Telescope and other observatories that merely orbit Earth, have actually traveled to other planets and approached the Sun, sending back pictures that humble or awe, even as they advance astronomers' understanding of our corner of the universe.
"The past decade has been spectacular in terms of achievements," says Sean Solomon, an astronomer at the Carnegie Institution of Washington and a leader of recent missions to Mercury and Mars.
Seven missions are currently keeping a wary eye on the Sun; they were launched by the United States, Japan and Europe, partly for pure science and partly for self-preservation. Solar flares, which can come from sunspots, are magnetic eruptions that sometimes hit Earth. A superflare like the one in 1859 that surged through telegraph lines and ignited fires would black out today's electrical grids, fry communication satellites and jam navigation signals. Missions to track solar flares may alert us to outsize magnetic storms in time to brace ourselves.
Last year, NASA's Messenger mission gave us the first up-close view of parts of Mercury, the planet closest to the Sun. The spacecraft has found extensive ridges along the planet's surface, made as it cooled and shrank over its four billion years. Messenger should nestle into orbit around Mercury in 2011 and continue to study the planet's geology and magnetic fields.
More missions—19 successful ones since the 1960s—have made it to Mars than any other planet, and it's the only planet whose surface we've explored with robots. NASA's Sojourner rover rolled along for three months in 1997; Phoenix performed direct experiments on soil samples during five months last year. The superstars of planetary exploration, the Spirit and Opportunity rovers, are still analyzing the Martian surface after five years. Thanks to all these efforts, we now know that Mars once had seas and rivers and there's ice there today. In the nine years before it went silent in 2006, the Mars Global Surveyor satellite detected many changes in the red planet, including the formation of two gullies, apparently by gushes of liquid water.
NASA's Galileo mission, focusing on the four Jovian moons that the Italian astronomer himself discovered 400 years ago, observed an atmosphere on Europa, ice at the poles and possibly an underground ocean. Callisto, too, may have a liquid ocean. Ganymede has a magnetic field, and Io sizzles with lava that reaches 3,140 degrees Fahrenheit. After the spacecraft ran out of fuel in 2003, engineers sent it crashing into Jupiter. Galileo went out in a blaze of observations.
For breathtaking beauty, no mission can compete with Cassini, which is run by the United States with contributions from 16 other nations. Zipping around Saturn and its moons since 2004, Cassini has detected odd spirals in Saturn's rings and a surprising amount of geologic activity on its moons. Titan, the largest (bigger even than Mercury), has lakes of supercool methane and slushy eruptions of a water-ammonia mix. Enceladus is riddled with geysers so powerful they feed matter into Saturn's rings. Rhea may have its own rings. Saturn is practically a solar system unto itself.
Pluto may not officially count as a planet anymore, but it has its own mission: NASA's New Horizons, now en route and expected to arrive in 2015.
Laura Helmuth is a senior editor at Smithsonian.



Comments
I would think a book should be published incorporating all of such things as the artical, lots of pictures and several chaptors, one for the sun and all the planets that have data.(incuding the non-planet Mercury.) hOWEVER, It would be best to keep the price below $50.00 as that would limit sales if higher. I would expect it to be coffee table size, with some 8 X 10 pictures....
Posted by James E. Lear on September 19,2009 | 12:45 PM
Thank you! Marvelous pictures!
Posted by Rebecah Propst on September 19,2009 | 02:41 PM
Beautful pictures and well-written article. Thank you.
Posted by Michael Praetorius on September 19,2009 | 04:55 PM
Speaking of MESSENGER, it approaches Mercury for a third time on Sept 29 and the historic event is being covered LIVE from Mission Control via Web 2.0. The pubic and particularly teachers and their classes are invited to PARTICIPATE in the adventure!
Read about how: http://bit.ly/TXrOs
Jeff Goldstein
Center Director
National Center fo Earth and Space Science Education
Posted by Jeff Goldstein on September 21,2009 | 07:11 AM
More Cassini images of Saturn can be found at:
http://ciclops.org
Posted by Joe on September 21,2009 | 01:34 PM
@ mr. goldstein
thanks for the info, but unfortunate typo you have there. happens to the best of us. ;)
Posted by marc on September 21,2009 | 02:35 PM
These are fabulous. And very low-res. Can you include links to the original hi-res versions?
Ken
Posted by ken on September 21,2009 | 02:59 PM
Here's one bigger image:http://commons.wikimedia.org/wiki/File:Saturn_eclipse.jpg
Posted by ken on September 21,2009 | 03:00 PM
Those are some of the most beautiful pictures of our solar system! Can anyone tell me – These pictures look so beautiful, amazingly so. I recognize some comments mention the picture has been enhanced with color to expose different facets, i.e., IR, sulphur explosions, etc. Other than for those purposes, are the pictures enhanced with color? I've always wanted to know if what I see is the real thing. Can anyone give me a definitive answer?
Posted by Dave Williamson on September 21,2009 | 03:06 PM
James Lear wants a book with the best images from the solar system. It's a bit old, but "Empire of the sun" by John R. Gribbin is certainly worth every penny.
Posted by Ole Henrik Fjeld on September 21,2009 | 03:44 PM
I wish your photo gallery had links to the original high definition versions of the images. This would let folks view them in more detail and/or download them for their own permitted usages.
Posted by Alan Claver on September 21,2009 | 04:57 PM
Awesome pictures!!
you misspelled geysers
Posted by Tim on September 22,2009 | 10:40 AM
I love these photos .I wish I could see much more of space and its grate wounders. I will like being aware of whats out there.
Posted by missy lopez on September 22,2009 | 01:39 PM
This is absolutely amazing. Some of the most breathtaking pictures that I've ever seen. Thank you, space program.
Posted by Spectator on September 22,2009 | 04:11 PM
Amazing pictures!!
Posted by JS on September 23,2009 | 08:55 AM
Extraordinary photos. Thank you so much for making them available.
Posted by Jerry Petty on September 25,2009 | 04:47 PM
AMAZING!!! These pictures are almost to beautiful to believe. Thanks..............
Posted by June Pair Smith on September 25,2009 | 06:06 PM
My grandsons and our entire family loved these amazing pictures. thanks..............
Posted by william t smith on September 25,2009 | 06:17 PM
It is striking how accurately Chesley Bonestell imagined many of the planetary objects that are now being photographed 50 years later. These new photos of Saturn are even more breathtaking than his paintings were.
Posted by James Wheat on September 25,2009 | 12:27 AM
Thanks for lovely images
Posted by Mukesh on September 28,2009 | 04:00 AM
It is so amazing that our solar system is so big but looks ssssssssssoooooooooooo small
Posted by lia waring on September 28,2009 | 10:23 AM
Absolutely awesome!!! Thank you for sharing these unbelievable images. In turn, I will forward them to my entire family and friends---Can't wait to hear the grandchildren's thoughts and ideas re a world they might dream about, but never have the opportunity to see in such majestic pictures!
Posted by rose cohen on October 2,2009 | 12:05 AM
These photos of the Solar Systen are positively marvelous and we have such incredible views!!!!! Thank you so very very much!
Posted by Mrs. Arlene Banos on October 5,2009 | 05:58 PM
Thanks for making these research photos available.
I will be using these with my Montessori students at school.
Posted by barbara lamb on October 7,2009 | 09:03 PM
How GREAT is our God and Creator Jesus Christ! His infinite handiwork is so beyond the finite mind of mankind!! Praise his name!!!!
Posted by Dee Cooper on October 8,2009 | 05:50 PM
These photos should be part of a book.
Posted by Frank Griffin on October 8,2009 | 08:57 PM
A Book of Pictures would be wonderful!
Posted by tm on October 8,2009 | 09:32 PM
Great pics!! When and where can I buy a compendium book containing these stunning photographs?
Sincerely,
Kenneth K. Kuehnl
Posted by Kenneth K. kuehnl on October 8,2009 | 11:38 PM
Unbelievable photos!! Hurray for NASA. Makes me realize how insignificant mankind is. We live in a glorious living universe.
Posted by B. Woods Mattingley on October 9,2009 | 04:11 AM
There is a wonderful book of photos entitled; Cosmos, A Field Guide, ISBN 1 905204 29 9 . It measures 14w x 17h inches so photos are large and dramatic.
Posted by steven arthur on October 10,2009 | 03:44 PM
beautiful pictures!!! is there any chance prints can be purchased?
Posted by P. Barone on October 12,2009 | 10:44 AM
Great photos, great article.
I put it all into a Power Point presentation and added some harmonica music: The way you look tonight. Thus, I emailed it to friends and familiy.
It looks fantastic.
Posted by William K. Boone Canovas on October 21,2009 | 08:51 PM
Agree that they should be published in book form. Since the photographs are in the public domain the price of such a book should be reasonable.
Posted by Fred Knox on October 22,2009 | 06:11 AM
Thank you, Smithsonian. The beauty brought tears to my eyes. I would love to have a large image for framing!
A thought: if those arrogant,self-possessed people in Washington, DC would kick back and look at the photos it might give them some much needed perspective!
Dottie Holding
Posted by Dottie Holding on October 22,2009 | 09:10 PM
que bonito
Posted by eli on October 31,2009 | 10:37 AM
Hola cool man
Posted by Ben pfeffer on November 4,2009 | 06:37 PM
Amazing, and appreciated.
Posted by Michael Proudfoot on November 12,2009 | 03:12 AM
WOW
I think the mass media is missing out on a great opportunity when they do not cover these explorations. We should not assume that because a human being is not doing the exploring that people would not be interested. The images alone would be enough to peak people's interest in the space program again.
Posted by Faith George on December 2,2009 | 04:18 PM