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Origin and evolution of life
Meteorites,Comets and Asteroids
Outer solar system
Moon to Mars
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Image of the Day
Arecibo. World’s largest dish, radio telescope. Puerto Rico.
Geostationary Operational Environmental Satellite image of Earth on the infrared channel, emphasizing thermal emissions and temperature differences rather than the visible light reflected one normally associates with oceanic and continental differences. The dark central area is a relatively humid zone of water vapor.
Soviet Venera 13 lander which parachuted to the Venusian surface on March 1, 1982
Hubble Deep Field. One of humanity’s most distant optical views of the Universe. What the Universe looked like in the extreme past, perhaps less than one billion years after the Big Bang.
A Triple-Planet System Orbiting Ups Andromedae. The Andromeda constellation, approximately 15 degrees wide x 20 degrees tall. Upsilon Andromedae is 10 degrees East (1/2 image width to the left) of the Andromeda Galaxy.
Humanity’s effort to send a message in a bottle for cosmic posterity. NASA’s Voyager 1 and 2 spacecraft are now over 10 billion kilometers from the Sun. 12-inch gold plated copper disk containing recorded sounds and images representing human cultures and life on Earth.
Earth as seen for its biological methane. A warming gas like carbon dioxide, its balance can drive temperatures to hot Venus or radiation-thin Mars depending on how industrial and agricultural influences on the planet are managed.
Stars with planets (red dots) found distributed across the celestial sky map shown with constellation locations.
This infrared Hubble Space Telescope view may contain the first ever direct image of a planet (lower left) outside our own solar system. The picture shows a very young double star located about 450 light-years away toward the constellation of Taurus. Cataloged as TMR-1 (Taurus Molecular Ring star 1
Continuous pressure from sunlight would ultimately accelerate a large solar sail to speeds about five times higher than possible with conventional rockets — without requiring any fuel. Using the same particle pressure that extends comet tails and shapes the earth’s magnetosphere are driven by the radiation pressure from the solar fusion reactions of heavy hydrogen to helium.
1997 Mars Pathfinder reveals the stunning landscape of a Martian day.
Earthshine. The reflected light from the moon of the earth gives astronomers a unique look at how a distant observer might detect life on earth, from the balance of elements (oxygen, water, ozone) and various colorful spectra of the blue marble.
Earthrise from afar. For the distant observer, the earth’s biological potential seems apparent to our trained eyes used to looking for oceans, atmospheric moisture and habitable regions. Apollo 8 crew shot from the lunar orbit.
VLA or very large array for radio astronomers. Each of the 27 radio telescopes in the Very Large Array (VLA) is the size of a house and can be moved on train tracks. Tres Montosas, New Mexico, USA
Omega Centauri. About 10 million stars orbit the center, the largest ball of stars in our galaxy
Angry solar flare and prominence. Continuous pressure from sunlight would ultimately accelerate a large solar sail to speeds about five times higher than possible with conventional rockets — without requiring any fuel. Using the same particle pressure that extends comet tails and shapes the earth’s magnetosphere are driven by the radiation pressure from the solar fusion reactions of heavy hydrogen to helium.
Arecibo message, Frank Drake, communicating heiroglyphic characters of our society, culture and science.
Dawn shot of the 70m antenna at Goldstone, California. Credit:NASA JPL
Dimitar Sasselov, professor of astronomy at Harvard University. Credit: Harvard News Office
Illustration of the possible formation process and present day structure of the planetary system around HD 68930. The three planets form from embryos originally located at larger distances (dashed ellipses) than the present ones (indicated by solid ellipses at 0.07, 0.18 and 0.63 the mean Earth-Sun distance). The embryos of the inner and middle planets start interior to the ice line, so that these two planets build up from rocky planetesimals and gas. The two planets consist of a central rocky core (in brown) and an envelope of gas (in gray). The embryo of the outermost planet starts beyond the ice line, and the planet accumulates a large amount of ice at the beginning of its formation. The planet finally consists of a central rocky core (brown), surrounded by a shell of water (ice or liquid – in blue), and a quite massive gas envelope (gray). Credit: ESO
The HARPS radial velocity measurements of HD 69830 are folded with the orbital periods of the three discovered planets: 8.67, 31.6 and 197 days, respectively. In each case, the contribution of the two other planets has been subtracted. The solid line shows the best fit to the measurements, corresponding to minimum masses of 10.2, 11.8 and 18.1 Earth masses. Note that the full span of the vertical axis is only 13 m/s! Error bars indicate the accuracy of the measurements. The integration time was 4 minutes on average for the first 18 measurements (shown as open dots), and was increased to 15 minutes for the remaining points (full dots). The latter measurements are therefore of much higher quality. Credit: ESO
Planetary System Around HD 69830 (Artist’s Impression) Credit: ESO
Planetary System Around HD 69830 (Artist’s Impression) This image is taken from a point of view inside the asteroid belt, which is assumed here to lie between the two outermost planets. Credit: ESO
Stockholm, Sweden — the site of the first Nordic Astrobiology conference in 2006. Photo Credit: Leslie Mullen
Pascale Ehrenfreund, of Leiden University in the Netherlands. Photo credit: Leslie Mullen
Polycyclic Aromatic Hydrocarbons. Credit: NASA/CalTech
origin of life montage. Credit: European Space Agency
Habitable zones for different types of stars, with our solar system as an example.
The Hubble Space Telescope has allowed astronomers to study atmosphericlayering on a giant planet far away from our Solar System.
The planet HD 209458b is shown here to scale with Jupiter and our Sun.The atmospheric structure of HD 209458b is outlined according to thedata gathered with Hubble.
A mysterious red glow that is present throughout the Milky Way and other galaxies could be due to very unusual, nano-sized, carbon and hydrogen rich particles made of polycyclic aromatic hydrocarbons (PAHs).Credit: NASA
In the process of photosynthesis, plants convert energy from the suninto chemical energy in the form of glucose, or sugar. The chlorophyllin plants absorbs more blue and red light from sunlight, and less greenlight. Chlorophyll is green, because it reflects green light more thanblue and red light.Credit: NASA Ames
This SeaWiFS satellite image shows chlorophyll (which indicates oceanplants) in the Earth’s oceans. The Normalized Difference VegetationIndex (NDVI) measures the amount and health of plants on land, whilechlorophyll a measurements indicate the amount of phytoplankton in theocean.Credit: SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE
The Hertzsprung-Russell diagram developed by 2 astronomers in 1912,plots some of the characteristics of a large number of stars. Theyplotted spectral class vs. luminosity (brightness) of a large sample ofstars. Our Sun’s luminosity is 3.9 x 1026 Joules/s. The plot spans alarge range in luminosity from a fraction of our Sun’s brightness (0.01times) to (10,000 times) much greater the strength of our Sun.Credit: NASA
Three simulated planets – one as bright as Jupiter, one half as brightas Jupiter and one as faint as Earth – stand out plainly in this imagecreated from a sequence of 480 images captured by the High ContrastImaging Testbed at JPL. The asterisk marks the location of the system’ssimulated star.Credit: NASA/JPL-Caltech
An infrared view of the Rosette nebula, with danger zones highlighted. Credit: NASA/JPL-Caltech/Univ. of Ariz.
The core of HD 149026b makes up a much larger percentage of the planet’smass than experts would have expected prior to the planet’s discovery.Credit: Greg Laughlin, UC Santa Cruz
Researchers measured the temperature of HD 149026b to be 3700 degreesFahrenheit. However, the side of the planet that faces away from itshost star could potentially be very cold.Credit: Gregory Laughlin
The Enterprise orbiting the fictitious planet Vulcan. (Star Trek imagescourtesy STARTREK.COM, Copyright 2007 CBS Studios Inc.)
The red dwarf star Gliese 581 is among the 100 closest stars to us,located only 20.5 light-years away in the constellation Libra (“theScales”).Credit: ESO Online Digitized Sky Survey
This artist’s impression shows the Gliese 581 system, including theEarth-like planet Gliese 581c.Credit: ESO
An artist’s impression of the MOST space telescope. MOST is asuitcase-sized microsatellite developed by the Canadian Space Agency,and is designed to study stars and extrasolar planets by measuring smalllight variations that are undetectable from the Earth’s surface.Credit: Canadian Space Agency
With more hydrogen and helium and less carbon, nitrogen and oxygen, Jupiter’s composition is more like the Sun than other Gas Giants.Credit: NASA
Resonant effects can be clearly seen in the radial distribution of the asteroids. Some orbital resonances are destabilizing, creating minima in the distribution, called “Kirkwood gaps,” after Daniel Kirkwood, the astronomer who first recognized them. The main asteroid belt is bounded by the 4:1 and 2:1 orbital resonances with Jupiter. The stable 3:2 and 1:1 resonances account, respectively, for the Hilda family asteroids and Jupiter Trojans. One astronomical unit is the Earth-Sun distance. (Distribution of asteroids courtesy of the Minor Planet Center.)
The main asteroid belt, situated in the broad region betweeen the orbits of Mars and Jupiter, contains countless rocky bodies (white points in diagram). The Trojan asteroids (pink) can survive outside this belt because they are locked in a 1:1 orbital resonance with Jupiter, which keeps them spaced safely about 60 degrees ahead or behind that giant planet in its orbit. For clarity, only asteroids larger than about 50 kilometers are plotted here. A space-probe image of the near-Earth asteroid Eros (above) gives a sense of what most asteroids probably look like. Eros is about 30 kilometers long, much too small for its gravity to make it spherical. (Diagram courtesy of the Minor Planet Center; image courtesy of NASA/Johns Hopkins UniversityApplied Physics Laboratory.)
Numerical simulations conducted by Jacques Laskar revealed that the maximum orbital eccentricity of the inner planets changes considerably over time. Thus over billions of years, each planet would cut a broad swath (colored bands) around its mean orbit (white lines). Indeed, Mercury´ orbital eccentricity can, in principle, become large enough that it risks collision with Venus. Although the orbits of other terrestrial planets will never cross in this way, they largely fill the inner solar system when one considers their long-term variations. (Adapted from Laskar 1996.)
Stable resonances are evident in the distribution of small bodies in the outer solar system (above). The Neptune Trojans, objectsin a 1:1 resonance with that planet, orbit some 30 astronomical units from the Sun. Reaching farther out are the orbits of the Kuiper-belt objects, including Pluto and the many “plutinos” (which share a stabilizing 2:3 resonance with Neptune) and objects locked into 3:4 and 1:2 resonances. Some of the plutinos (pink points at left) and otherKuiper-belt objects (white) are currently located within the orbit of Neptune. Transient comets and scattered Kuiper-belt objects are not shown for clarity. (Plan view courtesy of the Minor Planet Center.)
Numerical simulation reveals how the inner part of a planet-forming disk evolves. Initially, such a disk is composed of numerous planetesimals in near-circular (low-eccentricity)orbits (top). Within a few million years, orbital eccentricities grow to appreciable size for most of the smaller bodies, and planetary embryos form as smaller objects coalesce. As time goes on, the smaller bodies are swept up or scattered away, leaving a few planets in low-eccentricity orbits (bottom). (Adapted from Chambers 2001.)
Simulations suggest the wide variety of outer planetary systems that planetesimal disks can produce. The outer solar system is shown for comparison (a). The simulated planetary systems that resulted from these 11 experimental runs range from having just one (b) to as many as seven (f) outer planets of varying mass (indicated above each planet in Earth masses). The different outcomes depend on the initial arrangementof planetesimals and the chaotic interactions between them. (Adapted from Levinson et al. 1998.)
Studies of extrasolar systems offer astronomers increasing opportunity to test their ideas about planet formation. The three innermost planets of star 55 Cancri, for example, have orbits smaller than that of Mercury. These three planets are separated from a much more massive world by a region of apparent stability, which is predicted to harbor another planet. This region encompasses the star´ habitable zone, where surface temperatures would allow a suitable planet to support liquid water. The number above each planet in the bottom panel shows its minimum mass, expressed in Earth masses.
Some 4.6 billion years ago, before Earth existed, the Sun was surrounded by a disk of gas and dust, from which countless small bodies were forming. Most of these “planetesimals” coalesced into larger planetary embryos, which grew larger still to become the eight planets of the solar system. Why eight? There is nothing special about the number. Chaotic encounters between planetesimals early on led to a system with enough large bodies to sweep up most of the smaller ones. Computer simulations suggest that such encounters could as readily have ended up with fewer or more planets–”but not too many. The present configurationof the solar system is filled nearly to capacity, and additional planets would be dynamically unstable. (Artist´ rendering of a hypotheticalplanetary system in the making by T. Pyle, courtesy of NASA/JPL-Caltech.)
The Arecibo message was composed of the digital bits “one” and “zero”. A “one” was represented by an “on” radio pulse; a “zero” was represented by an “off” radio pulse. (The message starts: 000000101010100….). This picture was generated by arranging the 1679 bits into 23 columns of 73 rows, 23 and 73 being the two prime numbers, which, when multiplied together, equal 1679. A box representing a “one” is black, while a box representing “zero” is white.
The Parkes Radio Telescope in New South Wales, Australia. SETI’s Project Phoenix conducted observations here from February to June of 1995.
Researchers have demonstrated the formation of microscopic strands of helicalstructures in plasma clouds. The researchers say that these structures undergochanges that are normally associated with biological molecules like DNA and proteins- such as dividing and forming copies of the original structure.Credit: Tsytovich, V.N. et al. 2007
This artist’s impression shows what the disk of debris may look likearound the white dwarf star GD 362.Credit: Gemini Observatory/Jon Lomberg.
This images shows the relative size of GD 362 compared to Saturn and theEarth. Credit: Gemini Observatory/Jon Lomberg
In the foreground is the Teton Mountain Range of Wyoming, USA. On the far left, vast clouds of bright stars and dark dust are visible in the nearly vertical plane of our Milky Way Galaxy. On the left, just to the left of the southernmost Teton peak, the planet Jupiter is visible. Near the image center is the bright star Arcturus. Credit & Copyright: Wally Pacholka (Astropics.com); Image Processing: Tony Hallas.
The solar system’s habitable zone.
This digitally enhanced double-exposure was taken in May 2003 over the Kofa Mountains in Arizona, USA. Dark dust, millions of stars, and bright glowing red gas highlight the plane of our Milky Way Galaxy. Photo Credit: Richard Payne (Arizona Astrophotography)
This image from Spitzer shows the stellar nursery, called NGC 1333, that containsthe “steamy” young solar system, called NGC 1333-IRAS 4B. Credit: NASA/JPL-Caltech/ Harvard-Smithsonian CfA
Stars in the globular cluster NGC 6397. Credit: Hubble Space Telescope/ESA/NASA.
Stars in the globular cluster NGC 290. Credit: Hubble Space Telescope/ESA/NASA
Artist´ illustration of what plants may look like on different planets. Credit: Caltech/Doug Cummings.
The orbits of several extrasolar planets compared to Earth’s orbit. Many of the gas giant extrasolar planets orbit less than 1 AU from their host star, and have highly elliptical orbits.
This is an artist’s concept of an Earthlike planet around another star. Credit: NASA JPL
Astronomers have calculated the diameters of various types of planetsgiven certain compositions and masses. This image shows the relativesizes of six different kinds of planets with different compositions, anddepending on whether they have the same mass as Earth, or five times themass of Earth. Note that the 5-Earth-mass planets are larger than their1-Earth-mass counterparts, but they are not five times larger due to thegravitational compression that occurs when a planet’s mass is increased.The planets are shown silhouetted against the Sun, as if they aretransiting planets seen from afar. Credit: Marc Kuchner/NASA GSFC.
These theoretical models plot a planet’s size and mass given a certaincomposition. Future observations might be able to distinguish a purewater planet from a pure iron planet, but might have difficultydistinguishing a carbon planet from a silicate planet, for example.Click here to download an unlabeled version of this image. Credit: Marc Kuchner/NASA GSFC.
The Smith Telescope at the McDonald Observatory has a 2.7-meter mirror and was thethird largest in the world when it was built in the late 1960’s.Credit: McDonald Observatory
HIP 56948 is located 200 light-years away from Earth in the constellation Draco.Credit: Tim Jones/McDonald Obs./UT-Austin
This infrared image of the Pleiades star cluster –“ or Seven Sisters –“ was capturedby NASA’s Spitzer Space Telescope. The star HD 23514 is located in Pleiades, some400 light years away from Earth.Credit: NASA/JPL-Caltech/J. Stauffer (SSC/Caltech)
This artist’s rendering shows what the environment around HD 23514 might look like.Heat radiating from dust around the star indicates that there may have been a recentcollision between two large, rocky bodies – similar to the collision that formed theEarth’s Moon.Credit: Gemini Observatory/Lynette Cook
The Lyot Project will be attached to the Hale Telescope at the PalomarObservatory in California.Credit: NASA
Ben R. Oppenheimer, the principal investigator of the Lyot Project,makes adjustments to the coronagraph on a work bench.Credit: NASA
The first ground-based detection of an extrasolar planet’s atmosphere was performedusing the Hobby-Eberly Telescope (HET) at the McDonald Observatory.Credit: Marty Harris/McDonald Observatory.
NASA’s Kepler Mission will survey our region of the Milky Way galaxy to detecthundreds of Earth-sized and smaller planets near the habitable zone of their parentstars. Currently, the mission is set for launch in 2009.Credit: NASA
Arecibo Radio Telescope
SETI@home Chief Scientist, Dan Werthimer (right), and David Anderson, Project Leader (left).Credit:Planetary society
The study simulated planets with masses as much as 10 times that of Earth. Planetslarger than this have the potential to gather gas as they form and become more likeNeptune rather than rocky and ‘Earth-like’. The Voyager 2 spacecraft captured thisimage of Neptune, the fourth of our Solar System’s gas giants.Credit: NASA/JPL/Caltech
Our solar system´ habitable zone, which is where the temperature is suitable for liquid water. Credit: NASA
An artist´ impression of Gliese 876 d. Frozen planets in this system could harbor life. Credit: Trent Schindler and the National Science Foundation.
This illustration shows the dusty disk around the small star FN Tau.Because the mass of FN Tau is low, the disk is actually thicker in areasfurther away from the central star.Credit: National Astronomical Observatory of Japan
The CIAO instrument on Japan’s Subaru Telescope was used to capture thisinfrared image of the disk surrounding FN Tau. The star itself, locatedin the center of the disk, is blocked by the coronagraph mask.Credit: National Astronomical Observatory of Japan
The 8.2 meter Subaru Telescope is operated by the National AstronomicalObservatory of Japan, and is located atop Mauna Kea on the island ofHawaii.Credit: University of Hawaii
This artist’s concept shows a very young star encircled by a disk of gasand dust, the raw materials from which rocky planets such as Earth arethought to form. Credit: NASA/JPL-Caltech
This plot of infrared data shows the signatures of water vapor andsimple organic molecules in the disk of gas and dust surrounding a youngstar.Credit: NASA/JPL-Caltech
This image shows the discovery of KH 15D as captured by the Wesleyan 0.6m telescope. KH 15 D is a variable star found in the young cluster NGC2264.Credit: Wesleyan University/Van Vleck Observatory
Artist’s impression of the extrasolar planet HD 189733b, now known tohave methane and water.Credit: Credit: ESA, NASA and G. Tinetti (University College London, UK& ESA)
A wide star field image of the region around HD 189733b. The star HD189733 is located in the centre, just to the left of the planetarynebula Messier 27.Credit: NASA, ESA, and the Digitized Sky Survey 2. Acknowledgment:Davide De Martin (ESA/Hubble)
TESS will be used to detect planets as they transit in front of their parent stars.Credit: Spaceref
Astronomers are developing a new device that may be the first to spotEarth-like planets, like the hypothetical world with two moons shown inthis artist’s concept.Credit: David A. Aguilar (Harvard-Smithsonian Center for Astrophysics)
NASA´ Terrestrial Planet Finder is one of several instruments intended to detect planets around other stars. If Watson´ model is correct, even if some of those planets turn out to be Earth-like, they´re unlikely to host intelligent life.Credit: NASA/JPL.
The host star of GJ 436c is an 11th magnitude red dwarf and is estimated to have aradius that is about 42% of the Sun’s.
Experimental data from a NIST “gap-toothed” frequency comb that arefalse colored to indicate the range from low power (red) to high power(blue). The comb is specially designed for astronomy. Each “tooth” is aprecisely known frequency, and the teeth are widely separated (by 20gigahertz) in comparison to a standard comb.Credit: M. Kirchner & S. Diddams/NIST
The Low Frequency Array (LOFAR) consists of about 25,000 low-cost sensors (antennas, geophones and more) that will receive signals from space.Credit: LOFAR
The LOFAR array uses both low band and high band (pictured above) antennas. Electronic signals from the antennas are digitized and then sent to a central processor. Signals are combined using software to emulate a conventional antenna. Credit: LOFAR
Series of images showing the Moon transiting Earth, captured by NASA’s EPOXI spacecraft.Credit: Donald J. Lindler, Sigma Space Corporation/GSFC; EPOCh/DIXI Science Teams
View of crescent Earth from space. A glint of sunlight (marked with yellow lines) appears just west of the Galapagos and South America. Photo Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
This image of Earth was taken by Mars Global Surveyor, in orbit around Mars. Surface features and cloud cover can be distinguished over North America. Photo Credit: NASA/JPL/Malin Space Science Systems
Oceanic glint is shown as an unusually bright patch (yellow) on the dark ocean surface. Photo Credit: D.M. Williams, E. Gaidos.
The sparkle of Sunlight may be described as “specular reflection,” a mirror-like reflection in which incoming light from a single direction is reflected in a single outgoing direction.
Astronomers have found evidence for super-Earths, massive terrestrial planets orbiting distant stars. Someday we might be able to explore such alien worlds in order to search for life beyond our solar system. Image credit: NASA.
Artist’s representation of a rocky moon orbiting a gas planet in a binary star system. Image credit: NASA.
An artist’s rendering depicts planets colliding in a sun-like binarysystem about 300 light-years from Earth. Image Credit: Lynette R. Cook
Artist’s impression of the planetary system around the red dwarf Gliese 581. The five Earth-mass planet (seen in foreground – Gliese 581 c) is just inside the habitable zone. Credit: ESA
Artist’s impression of the five-Earth mass planet, Gliese 581 c. Credit: ESA
Plateau de Bure Interferometer. Credit: Rebus
This artist’s concept illustrates a dead star, or “white dwarf,” surrounded by the bits and pieces of a disintegrating asteroid. Image credit: NASA/JPL-Caltech
The NASA Infrared Telescope Facility –” at the summit of Mauna Kea, Hawaii –” was one of the telescopes that detected martian methane in 2003. Credit: NASA/University of Hawaii
Costa Rica Balls
Arecibo message long
W.M. Keck Observatory
Gran Telescopio Canarias
Apodizing Phase Plate
Apodizing Phase Plate2
La Silla 2.2
Large Binocular Telescope
Laser Interferometer Space Antenna
Robert C. Byrd Green Bank Telescope
Mount John University Observatory
Swiss Crop Circle
habital zones by orbital area
Lovell radio telescope
Arecibo Observatory facility
supernova on alien world
Optical Ground Station
Allen Telescope Array
ESA’s Perth station
Allen Telescope Array (ATA)
Allen Telescope Array (ATA) second view
1.54-metre telescope at La Silla Observatory
Spectrum of light
KELT North telescope
SKA at night
SKA’s low frequency antennas
Giant Cyclops array
ESO and Leonhard Euler telescopes
Planet around Alpha Centauri B
Bright Alpha Centauri
Probability of finding Earth’s nearest extra terrestrial civilization
Kitt Peak National Observatory
The Project 1640 instrument
Close Encounters of the Third Kind
Table of the three parameters which result on a Q value and the reliability factor δ
The Rio Scale
Mayall Telescope interior
The Atacama Large Millimeter/submillimeter Array (ALMA) in Chile
A laser at the Very Large Telescope (VLT)
The Amazing Lunar Laser show
Onsala Space Observatory
Silhouette of the Atacama Pathfinder Experiment (APEX) at Chajanantor, in the Atacama Desert, Chile. Credit: ESO
An artist’s conception depicting extraterrestrial life.
NASA’s Infrared Telescope Facility in Hawaii allowed scientists to take a closer look at the composition of Ceres. Credit: Ernie Mastroianni
The SOAR 4.1-m telescope on Cerro Pachón. Credit: CTIO