© Lucasfilm Ltd. & TM. All Rights Reserved
Luke Skywalker surveys a double sunset on the planet Tatooine in "Star Wars: A New Hope."
updated 10/22/2010 6:46:48 PM ET 2010-10-22T22:46:48

It's one of the most famous sci-fi scenes in cinematic history: Luke Skywalker standing in the desolate surroundings of his home watching the twin sunset on his homeworld of Tatooine in "Star Wars: A New Hope." Tatooine, a habitable world (or it was until the Rakata race plundered the planet of its natural resources), exists in the fictional binary star system of Tatoo.

But how realistic is it to have a stable planet orbiting one (or both) of the stars in a binary system? According to some fascinating research led by astronomers at Tennessee State University, such a double-sunset scene may not be too farfetched.

By developing a technique called precision astrometry, the researchers have discovered a Jupiter-mass exoplanet orbiting the primary star of the binary system of HR 7162 (or HD 176051), 49 light-years from Earth. They've called it "Inrakluk."

  1. The planet boom
    1. Hunt for new worlds goes into overdrive
    2. Looking for alien Earths? Here they come
    3. Interactive: The new solar system
    4. Pluto debate is about more than one little world
    5. Cosmic Log: Planets on the Web
    6. Interactive: The search for extrasolar planets

Astrometry is the study of the precise measurements of the positions and movement of stars. This is the first time the technique has been used to decipher the presence of an exoplanet in the complex dynamics of a binary system. The periodic variation in location of HR 7162 led to the Jupiterlike exoplanet's discovery.

But the very existence of Inrakluk has called into question our understanding about how planetary systems form.

In a one-star system like our solar system, the leading theory as to how the planets formed is through a process called accretion. The young solar system would have looked vastly different than it does today; a juvenile sun surrounded by a disk of gas and dust. Over the course of millions of years, this accretion disk would have become more "clumpy." As it cooled, the dust would stick together, slowly forming the rocky seeds of planetary cores.

These protoplanets would gradually exert a gravitational pull on the local volume of space, pulling in more and more material. Eventually, the planets came into being, vacuuming up the rest of the planet-building debris surrounding the sun.

This is all well and good for a single star, but what if you throw a second star into the mix, like in the HR 7162 binary? The accretion model for planetary formation simply doesn't stick.

When there's a second star orbiting the primary (more massive) star in the binary, according to planetary evolution models, the combined gravitational tugging of both stars hinder the slow accretion of the planets. The planet-building materials are ejected from the system before planets can form. This is one reason put forward that may explain why so few exoplanets have been discovered in binary systems.

However, this new discovery proves that mature Jupiter-type worlds can exist in binaries. The TSU-headed group have challenged the planetary accretion theory as the sole planet-forming mechanism in favor of a faster "gravitational collapse" model.

  1. Most popular

Models predict that binary stars can create a very turbulent environment for planetary formation. Some regions in these systems could become "overdense." Large collections of dust are corralled together where the mutual gravity of the cloud causes it to rapidly collapse. In this case, the formation of Jupiter-mass worlds may only take a few thousand years to form, well before the planet-building materials are ejected from the system.

But where does that leave Tatooine? Well, for starters, Inrakluk is a gas giant, so there's no surface for Luke to stand on to admire a double sunset. Also, the two stars depicted in Luke's double sunset appear to be close together, so the system of Tatoo is most likely a compact binary where the stars orbit very closely. According this research, the exoplanet orbits the primary star, whereas the binary partner orbits the pair. But that doesn't mean a double sunset isn't possible if the alignment is right.

According to Matthew Muterspaugh, a TSU astronomer and the study's lead scientist, his team's development of astrometry could be refined to hunt for Earthlike exoplanets:

"The study of planets and their origins is important for many reasons to humanity. Understanding that there are other planets like our own, helps us better understand how our own planet came to be and how we, as human beings, came to be and where we are going. The techniques we’re developing could help us better locate Earthlike planets in our local neighborhood in the galaxy."

© 2012 Discovery Channel

Video: New frontiers in planetary science

Photos: Month in space: September 2010

loading photos...
  1. Martian sea of sand

    Near Mars' north pole, the landscape is dominated by sand dunes forming a massive erg, or sand sea, much like parts of the Sahara Desert on Earth. In parts of the erg, sand is abundant and covers the entire surface. Here, near the edge, sand is in shorter supply and the dunes are separated by areas of lighter-toned soil. This color-coded image from NASA's Mars Reconnaissance Orbiter was captured in July and published on Sept. 1. (NASA /JPL/ University of Arizona) Back to slideshow navigation
  2. Dance of the galaxies

    NGC 5426 and NGC 5427 are two spiral galaxies of similar sizes engaged in a dramatic dance. It is not certain that this interaction will end in a collision and ultimately a merging of the two galaxies, although the galaxies have already been affected. Together known as Arp 271, this dance will last for tens of millions of years. This image, released Aug. 30, was taken with the EFOSC instrument attached to the New Technology Telescope at the European Southern Observatory's La Silla facility in Chile. (ESO) Back to slideshow navigation
  3. Crazy cones on Mars

    These Martian volcanic cones are similar in size and shape to cones found in Iceland, where hot lava has run over wet ground. The heat from the lava boils the water, which bursts through the lava flow. These steam-driven exploding bubbles of lava throw chunks of molten and solid lava into the air. A long series of such explosions is needed to build up one of the large cones. This image, released Sept. 1, was taken by a high-resolution camera on NASA's Mars Reconnaissance Orbiter. (NASA via AP) Back to slideshow navigation
  4. Creating Curiosity

    Engineers work on the Curiosity rover at NASA's Jet Propulsion Laboratory in Pasadena, Calif., on Sept. 16. Curiosity, also known as the Mars Science Laboratory, is due to be launched to the Red Planet from Cape Canaveral Air Force Station in Florida in late 2011. (Jae C. Hong / AP) Back to slideshow navigation
  5. Igor the Terrible

    A photo taken from the International Space Station on Sept. 15 shows Hurricane Igor whirling through the Atlantic Ocean hundreds of miles below. In the foreground you can see a Russian spacecraft docked to the space station. (NASA via AFP - Getty Images) Back to slideshow navigation
  6. Dodging a bullet

    An extreme ultraviolet image from NASA's Solar Dynamics Observatory shows an exceptionally heavy plasma eruption on the surface of the sun on Sept. 8. Not to worry, though: The resulting blast of electrically charged particles missed Earth. (NASA/SDA via EPA) Back to slideshow navigation
  7. Bull's-eye on the moon

    A color-coded topographic map based on data from NASA's Lunar Reconnaissance Orbiter shows the 580-mile-wide Mare Orientale, the largest young impact basin on the moon. This basin formed when a projectile hit the moon about 3.8 billion years ago and penetrated deeply into the lunar crust, ejecting huge amounts of material. The image was released Sept. 16 to coincide with the publication of scientific papers about LRO's mission. (NASA / Goddard / MIT / Brown) Back to slideshow navigation
  8. Two flashes from Jupiter

    A fleeting bright dot on each of these images of Jupiter marks a small comet or asteroid burning up in the atmosphere. The image on the left was taken on June 3 by Australian amateur astronomer Anthony Wesley, with a fireball appearing on the right side. The image on the right was taken by Japanese amateur astronomer Masayuki Tachikawa on Aug. 20, with a fireball appearing at upper right. In a report published Sept. 9, NASA said neither event left a lasting mark on the planet. (NASA via Reuters) Back to slideshow navigation
  9. Spiral in space

    A picture from the Hubble Space Telescope, published Sept. 7, shows an unusual spiral nebula around the star LL Pegasi, 3,000 light-years from Earth. Astronomers say the spiral shape was created by material swirling out from one of the stars in a binary-star system. (ESA / NASA) Back to slideshow navigation
  10. Bootprint on Mars?

    Orcus Patera is an enigmatic elliptical depression near Mars' equator, in the eastern hemisphere of the planet. Located between the volcanoes of Elysium Mons and Olympus Mons, its formation remains a mystery. The favored theory is that the feature was created when a comet or asteroid hit the Red Planet at a shallow angle. This picture of Orcus Patera, released Aug. 27, was taken by the European Space Agency's Mars Express orbiter. (ESA) Back to slideshow navigation
  11. NASA's six-legged robot

    The All-Terrain Hex-Limbed Extra-Terrestrial Explorer, or ATHLETE, is a prototype heavy-lift utility vehicle designed to support future human exploration of extraterrestrial surfaces. ATHLETE got a chance to flex its limbs on Sept. 15 in northern Arizona during NASA's Desert RATS field tests. (Robyn Beck / AFP - Getty Images) Back to slideshow navigation
  12. Practicing for Mars

    Geologists Jacob Bleacher and Jim Rice take a close look at a rock formation in northern Arizona before collecting samples on Sept. 5. The geologists took part in NASA's Desert RATS exercise, which is aimed at trying out the equipment and procedures that could come into play during a mission to Mars or other interplanetary destinations. The "RATS" in the name stands for "Research and Technology Studies." (NASA Desert RATS) Back to slideshow navigation
  13. Ice sculptures in space

    Clouds of gas and dust in the Carina Nebula are sculpted into bizarre shapes by stellar radiation, as seen in this image captured by the Hubble Space Telescope and unveiled on Sept. 16. The Hubble team compares the pillars to "cosmic ice sculptures." (NASA, ESA, and the Hubble Heritage Project) Back to slideshow navigation
  14. New York at night

    New York City is ablaze in an image sent by NASA astronaut Doug Wheelock from the International Space Station on Aug. 28. "The City That Never Sleeps," he wrote in a Twitter tweet. "New York, New York on a clear summer night." (Doug Wheelock / NASA via AP) Back to slideshow navigation
  15. Shooting a laser at the sky

    This image, released on Sept. 6, shows a laser beam shooting up from the European Southern Observatory’s Paranal Observatory in Chile. The laser beam is used as a guide for the observatory's adaptive-optics system, which compensates for unsteadiness in the atmosphere to produce sharper astronomical images. (Y. Beletsky / ESO) Back to slideshow navigation
  16. Thar she blows!

    A solid rocket motor that could be used on future NASA launch vehicles is tested Aug. 31 at ATK Aerospace Systems' test site in Promontory, Utah. The rocket motor burned for just over two minutes during the successful static test, producing about 3.6 million pounds of thrust. (ATK) Back to slideshow navigation
  17. The road ahead

    NASA's Opportunity rover looks across a series of sand ripples and bedrock outcrops toward the rim of Endeavour Crater on the horizon on Sept. 6. Opportunity has just crossed the halfway mark in its trip from Victoria Crater to Endeavour. The rover headed out from Victoria in September 2008. (NASA / JPL-Caltech) Back to slideshow navigation
  18. Saturn and its children

    Four of Saturn's moons join the planet for a well-balanced portrait, released by the Cassini orbiter's imaging team on Sept. 10. Saturn's largest moon, Titan, is at lower left. Tethys is at upper right. Two much smaller moons, Pandora and Epimetheus, are barely visible near the rings. (NASA/JPL/Space Science Institute) Back to slideshow navigation
  19. Moon and Earthglow

    A crescent moon is just about to set below Earth's glowing horizon in a picture taken Sept. 4 from the International Space Station. The glow is sunlight scattered by Earth's atmosphere. (NASA via Reuters) Back to slideshow navigation
  20. Twilight of the shuttle

    Photographers gather early on the morning of Sept. 21 to take pictures of the space shuttle Discovery, just after its arrival at the launch pad. Discovery is scheduled to embark on the shuttle fleet's penultimate mission on Nov. 1. The final shuttle flight, involving Endeavour, is set for launch in February - although there's a chance that one additional mission will be flown. (Scott Audette / Reuters) Back to slideshow navigation
  1. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  2. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  3. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.

  4. Editor's note:
    This image contains graphic content that some viewers may find disturbing.

    Click to view the image, or use the buttons above to navigate away.


Discussion comments


Most active discussions

  1. votes comments
  2. votes comments
  3. votes comments
  4. votes comments