For nearly 20 years, the Hubble Space Telescope has dazzled us with unprecedented views of the cosmos—from the splendor of our celestial neighborhood to galaxies billions of light years away. A new IMAX film, Hubble 3D is blasting off at HMNS on Mar. 19. Be sure to look at some of the amazing photos of the universe around us, courtesy of NASA.
Hubble 3D will transport you to galaxies that are 13 billion light years away, back to the edge of time.
Just can’t wait until March 19? Never fear – IMAX is releasing webisodes from the production of the film, and we’ll be featuring them here on the blog.
In the first webisode, find out what happens when you launch a billion dollar telescope with an off-kilter lens – and just how delicate this spectacular instrument really is. In this behind the scenes interview, astronaut Mike Massimino talks about his space mission to repair the Hubble Telescope in May of 2009.
Jupiter is the brightest planet or star in the evening sky this month. Face south and look for the brightest point of light there. If you’re looking in the right direction, you can’t miss it. Jupiter can currently be found inside the constellation Capricornus.
Venus begins to wrap up its stint as morning star this month, as it’s now much lower in the pre-dawn sky. Look southeast right as day begins to break for the brightest thing (other than the Moon.) Venus remains the ‘morning star’ for the rest of 2009. Mars is now almost overhead at dawn. It is also brightening as the Earth approaches it. Saturn is now also visible in the morning sky, but it is not as bright as Venus.
The Big Dipper happens to be to the lower left of the North Star at dusk this month; you’ll need a clear northern horizon to get a good look at it. Sagittarius, the Archer, known for its ‘teapot’ asterism, is in the southwest. Look for the enormous Summer Triangle, consisting of the stars Deneb, Vega, and Altair, high in the west. As familiar summer patterns shift to the west, the constellations of autumn take center stage. The Great Square of Pegasus is high in the east at dusk. The star in its upper left hand corner is also the head of Andromeda. Facing north, you’ll see five stars in a distinct ‘M’ like shape—this is Cassiopeia, the Queen. Her stars are about as bright as those in the Big Dipper, and she is directly across the North Star from that Dipper. In fall, while the Dipper is low, Cassiopeia rides high.
You will notice that November evening skies are generally dimmer than skies in summer or winter. This is because we are facing out of the galactic plane. Our Milky Way is quite flat—about 100 times as wide as it is thick. As a result, most stars, including most of the brighter stars, are near the plane of the Galaxy. We therefore see fewer bright stars when looking perpendicular to this plane, as we do when we face south on November evenings.
Our Galaxy is part of a Local Group of about 40 galaxies. This group, in turn, is on the edge of the Virgo Supercluster of galaxies. It turns out that when we look up in November, we have our backs to the center of that huger supercluster and are facing our own Local Group. Thus, other members of that group, such as the Andromeda Galaxy and the Triangulum Galaxy, are high in the sky. On May evenings, when we again look out of our galaxy plane, we’ll be facing the center of the Virgo Supercluster and have our backs to our own Local Group.
Moon Phases in November 2009:
Full November 2, 1:14 pm
Last Quarter November 9, 9:57 am
New November 16, 1:13 pm
1st Quarter November 24, 3:38 pm
Today, the just-past-full Moon will pass very close to a star cluster called the Pleiades. At 9:11 p.m. and again at 10:11 (CST), it will briefly occult (hide) a couple of its stars.
The idea that other life-bearing worlds are out there continues to fire our imaginations, as attested by the success of the recently-opened Star Trekmovie, and by the critically acclaimed Battlestar Galacticaseries which concluded earlier this spring.
In 1995, astronomers identified the first exoplanet around the star 51 Pegasi, nicknamed Bellerophon. Since then, we’ve found over 300 planets around other stars. For many years, though, we were finding only ‘hot Jupiters’ – gas giants extremely close to the host star (such as Bellerophon.) These are not logical places to search for Mr. Spock, or for that matter any kind of life as we know it. However, the search for extra-solar planets or exoplanets (planets around stars other than our Sun) is now entering a new phase. As we refine our methods and our tools, we are at last beginning to find planets much smaller than Jupiter, approaching Earth in size. And we’re starting to find some planets in the habitable zones of stars, regions where the temperature is neither too hot nor too cold for life. Although we don’t really expect to find another Vulcan or Caprica, two recent announcements can give us some insight into how the search is done.
In April, astronomers announced the discovery of Gliese 581 e, the fourth planet found around the star Gliese 581. At around two Earth masses, this is the least massive planet ever found outside our solar system. Astronomers also announced that Gliese 581 d(the third planet found in the system) is within the star’s habitable zone. (‘A’ would designate the star itself; the planets are b, c, d, and e.) This is star #581 in Wilhelm Gliese’s Gliese Catalogue of Nearby Stars, an effort to list all stars less than 25 parsecsfrom the Sun. Gliese 581 is about 20 light years away, located in the constellation Libra.
Astronomers found Gliese 581’s planets using the radial velocity method. Perhaps you are familiar with the Doppler effect, in which a sound changes in frequency when a source that had been approaching begins to move away. We see the same effect with receding and approaching sources of light. When a light source is receding from us, the wavelength of its light gets longer (and therefore redder.) When a light source is approaching, the wavelength of its light gets shorter (and therefore bluer.) The spectra of stars show dark absorption lines, indicating wavelengths of light absorbed by gases in the star. By observing these lines over time we see that some stars show a slight redshift, then a slight blueshift, then a slight redshift…. Such a periodic variation indicates that the star is being tugged by something orbiting it. The size and period of the tug gives us an idea of the tugger’s mass. A mass much less than our Sun and comparable instead to Jupiter indicates a planet.
To understand how hard it is to find Earth-sized planets this way, imagine if a crewman on Galactica had to find Earth with this method. Our observer needs to see an entire oscillation to recognize the periodic tug of a planet, so (s)he must observe the Sun for a full year (Earth’s entire orbital period) to detect our planet. Further, Jupiter’s tug on our Sun overwhelms Earth’s by about a factor of 12. Any distant observer studying our own Sun’s radial velocity would probably notice only Jupiter’s influence on our Sun. And that would take about 12 years of observing, since Jupiter takes about that long to orbit the Sun. Finally, the observer needs to see our solar system roughly edge on, such that planets tug the Sun towards and away from the observer. Fortunately for Starbuck et. al., Galactica has access to much better technology than we do today.
Gliese581 is type M3V. Here ‘V’ is the Roman numeral five, representing the fifth luminosity class, which is the main sequence of stars that includes our Sun. ‘M3′ indicates a reddish star significantly smaller and cooler than our Sun. In particular, Gliese 581 has less than one-third our Sun’s mass and is more than 2000K (3600 oF) cooler than our Sun. Therefore, the habitable zone around Glises 581 is much closer to the star than ours is to our Sun. Gliese 581 d, orbiting in that zone, orbits once in 67 Earth days. Although Gliese 581 e takes only about 3 days to orbit its star once, is the planet closest to Earth’s mass we have yet identified. The Gliese 581 system brings us closer to finding planets like ours and to understanding solar systems like our own.
Just days ago (May 13,) NASA announced that its Kepler telescope, launched March 6, is ready to begin observations. This is NASA’s first mission capable of finding Earth-sized and smaller planets around stars other than our Sun. Unlike the Hubble telescope which orbits Earth, this telescope is in orbit around the Sun. It is roughly at Earth’s distance from the Sun, but on an orbit where it lags slightly more behind Earth’s position as time passes. After 4 years, Kepler will be about 0.5 AU, or half the Earth-Sun distance, behind Earth on its orbit.
Kepler will stare continuously at the same small region of the sky for three and a half years. Scientists did not want this steady gaze interrupted by day-night cycles or by passage behind the Earth, as would happen if the telescope were in Earth’s orbit. Further, Kepler is looking at a region of space far above the plane of our solar system, so the Sun, Moon, and other solar system bodies never come near the field of view. That area of space is also in the galactic plane roughly in the direction the Sun itself is traveling. This means we are observing stars at the Sun’s approximate distance from the galactic core.
Kepler will detect extrasolar planets using the transit method. This method involves looking at stars continually for long periods of time to see if the light ever gets slightly dimmer. If the slight dimming occurs on a regular basis, it might be because a planet is orbiting the star and regularly passing in front of it from our perspective. Such a passage is called a transit. When a planet as small as our Earth transits its star, the star dims by only a factor of 1/10,000. Only now, with Kepler, do we have an instrument powerful enough to detect such a tiny change in a star’s brightness. Of course, we need to be fortunate enough to observe the planetary system edge-on, otherwise no transit will occur. However, the chosen field of view contains about 100,000 stars, so odds are at least a few are oriented favorably.
Even if we do find other Earth-sized planets, however, we are still far from finding alien cultures, much less interacting with them as in science fiction. Aliens in science fiction can interact because writers cheat on the laws of physics by introducing a parallel dimension. This dimension is called ‘subspace’ in Star Trek and ‘hyperspace’ in Star Wars and Babylon 5. To travel from one planetary system to the next, a starship leaves space, enters subspace/hyperspace, travels through that dimension, and reemerges into space at its destination. As far as we know, however, no subspace or hyperspace exists to shorten space travel; real spacecraft must travel through space. That makes the speed of light (300,000,000 m/s) an inviolable speed limit. For example, nothing can travel between our system and that of Gliese 581 in less than 20 years, because Gliese 581 is 20 light years away.
What’s more, any life we hope to find and interact with has to exist at the same time we do. Given our short existence compared to the universe as a whole (equivalent to eight minutes out of a year), this could be the single biggest limitation on our ability to find other worlds with life.
But even as we leave green-blooded aliens and warp drive at the theater, a quite real adventure remains before us. No matter how much we explore and study our solar system, we cannot truly understand it until we can place it in a larger context. The Kepler mission promises to show us more systems like our own, or to show us just how rare systems like ours are. Either way, we will be able to appreciate our own Earth and familiar planets like never before. I find that as thrilling as a ride with Captain Kirk.
Happy New Year! Tomorrow is the first day of 2009. So what an appropriate time to look back and see what we have accomplished in science over the past years on this day.
On New Years Day, 1801, the dwarf planet Ceres was discovered by Giuseppe Piazzi. This dwarf planet is actually located inside our solar system, it is part of the asteroid belt between Mars and Jupiter. Astronomer Johann Elert Bode had suggested nearly forty years earlier that their might be large planets or land masses between Mars and Jupiter based off a theory (that is no longer used) proposed in 1766 by Johann Daniel Titus. It was this same theory that led to the discovery of Uranus in 1781. Because of the theory and the unknown location of a planet between Mars and Jupiter, 24 astronomers combined their efforts and began a methodical search for the planet.
On New Years day, 1925, the American astronomer Edwin Hubble announced the discovery of galaxies outside of our own milky way. Hubble also later showed that the universe is still expanding.
On New Years Day, 1985, the Internet domain name system was created. The domain name system translates human names for sites into the numerical or binary identifiers associated with network equipment. A simple explanation is that the Internet domain name system acts as a “phone book” for the Internet by translating a human-friendly host name into an IP address.
On New Year’s Day, 1995 the existence of freak waves was proven. The Draupner oil platform in the north sea was usually hit by large waves measuring about 39 feet in height. However, on Jan 1st of that year a freak wave that was 89 ft tall crashed down on the platform. Freak waves had been thought to exist before based off of stories of sailors, but it had never previously been recorded.