News, Updates, and Resources for How Big is the Universe?

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Online Articles

    • 2013-03-20. Planck Mission Brings Universe into Sharp Focus | NASA RELEASE: 13-079. Excerpt: ...The Planck space mission has released the most accurate and detailed map ever made of the oldest light in the universe, .... The map results suggest the universe is expanding more slowly than scientists thought, and is 13.8 billion years old, 100 million years older than previous estimates. The data also show there is less dark energy and more matter, both normal and dark matter, in the universe than previously known. ...Planck launched in 2009 and has been scanning the skies ever since, mapping the cosmic microwave background, the afterglow of the theorized big bang that created our universe. This relic radiation provides scientists with a snapshot of the universe 370,000 years after the big bang. Light existed before this time, but it was locked in a hot plasma similar to a candle flame, which later cooled and set the light free. ...The newly estimated expansion rate of the universe, known as Hubble's constant, is 67.15 plus or minus 1.2 kilometers/second/megaparsec. ...The new estimate of dark matter content in the universe is 26.8 percent, up from 24 percent, while dark energy falls to 68.3 percent, down from 71.4 percent. Normal matter now is 4.9 percent, up from 4.6 percent. ...For more information about Planck, visit: http://www.nasa.gov/planck and http://www.esa.int/Our_Activities/Space_Science/Planck .... See full article at http://www.nasa.gov/home/hqnews/2013/mar/HQ_13-079_Planck_Mission.html.

    • 2012-12-12. NASA's Hubble Provides First Census of Galaxies Near Cosmic Dawn | NASA RELEASE : 12-428. Excerpt: WASHINGTON -- Using NASA's Hubble Space Telescope, astronomers announced Dec. 12 they have seen further back in time than ever before and have uncovered a previously unseen population of seven primitive galaxies that formed more than 13 billion years ago, when the universe was less than 3 percent of its present age. The deepest images to date from Hubble yield the first statistically robust sample of galaxies that tells how abundant they were close to the era when galaxies first formed. …The results show a smooth decline in the number of galaxies looking back in time to about 450 million years after the theorized big bang. The observations support the idea galaxies assembled continuously over time and also may have provided enough radiation to reheat, or reionize, the universe a few hundred million years after the big bang… estimated to be 13.7 billion years old. … said Brant Robertson of the University of Arizona in Tucson. "There wasn’t a single dramatic moment when galaxies formed. It was a gradual process." More info - http://hubblesite.org/news/2012/48 …. Read the full article: http://www.nasa.gov/home/hqnews/2012/dec/HQ_12-428_Hubble_UDF.html

    • 2012-11-15 NASA's Great Observatories Find Candidate for Most Distant Galaxy NASA RELEASE : 12-397. Excerpt: By combining the power of NASA's Hubble and Spitzer space telescopes and one of nature's own natural "zoom lenses" in space, astronomers have set a new record for finding the most distant galaxy seen in the universe. The farthest galaxy appears as a diminutive blob that is only a tiny fraction of the size of our Milky Way galaxy. But it offers a peek back into a time when the universe was 3 percent of its present age of 13.7 billion years. The newly discovered galaxy, named MACS0647-JD, was observed 420 million years after the big bang, the theorized beginning of the universe. Its light has traveled 13.3 billion years to reach Earth.

    • This find is the latest discovery from a program that uses natural zoom lenses to reveal distant galaxies in the early universe. The Cluster Lensing And Supernova Survey with Hubble (CLASH), an international group led by Marc Postman of the Space Telescope Science Institute in Baltimore, Md., is using massive galaxy clusters as cosmic telescopes to magnify distant galaxies behind them. This effect is called gravitational lensing.

    • …MACS0647-JD is so small it may be in the first steps of forming a larger galaxy. An analysis shows the galaxy is less than 600 light-years wide. … For comparison, the Large Magellanic Cloud, a dwarf galaxy companion to the Milky Way, is 14,000 light-years wide. Our Milky Way is 150,000 light-years across. See full release: http://www.nasa.gov/home/hqnews/2012/nov/HQ_12-397_Hubble_Farthest_Galaxy.html

    • 2012-10-03. NASA's Infrared Observatory Measures Expansion of Universe | NASA RELEASE : 12-343. Excerpt: …Astronomers using NASA's Spitzer Space Telescope have announced the most precise measurement yet of the Hubble constant, or the rate at which our universe is stretching apart. …It improves by a factor of 3 on a similar, seminal study from the Hubble telescope and brings the uncertainty down to 3 percent, a giant leap in accuracy for cosmological measurements. The newly refined value for the Hubble constant is 74.3 ± 2.1 kilometers per second per megaparsec. A megaparsec is roughly 3 million light-years. …Glenn Wahlgren, Spitzer program scientist … said infrared vision, which sees through dust to provide better views of variable stars called cepheids, enabled Spitzer to improve on past measurements of the Hubble constant. … Cepheids are crucial to the calculations because their distances from Earth can be measured readily. In 1908, Henrietta Leavitt discovered these stars pulse at a rate directly related to their intrinsic brightness. …By measuring how bright they appear on the sky, and comparing this to their known brightness as if they were close up, astronomers can calculate their distance from Earth.

    • Spitzer observed 10 cepheids in our own Milky Way galaxy and 80 in a nearby neighboring galaxy called the Large Magellanic Cloud. … "Just over a decade ago, using the words 'precision' and 'cosmology' in the same sentence was not possible, and the size and age of the universe was not known to better than a factor of two," said Freedman. "Now we are talking about accuracies of a few percent." … Read the full article: http://www.nasa.gov/home/hqnews/2012/oct/HQ_12-343_Spitzer_Cepheid.html

    • 2011 Jan 12. Cosmology Standard Candle Not So Standard After All. NASA Spitzer Project. Excerpt: PASADENA, Calif. Excerpt: Astronomers have turned up the first direct proof that "standard candles" used to illuminate the size of the universe, termed Cepheids, shrink in mass, making them not quite as standard as once thought. The findings, made with NASA's Spitzer Space Telescope, will help astronomers make even more precise measurements of the size, age and expansion rate of our universe.

    • 2010 October 6. NASA RELEASE 10-244: NASA's WMAP Project Completes Satellite Operations Mission Observed Universe's Oldest Light. Excerpt: After nine years of scanning the sky, the Wilkinson Microwave Anisotropy Probe (WMAP) space mission has concluded its observations of the cosmic microwave background, the oldest light in the universe. The spacecraft has not only given scientists their best look at this remnant glow, but also established the scientific model that describes the history and structure of the universe.

    • …WMAP was designed to provide a more detailed look at subtle temperature differences in the cosmic microwave background that were first detected in 1992 by NASA's Cosmic Background Explorer (COBE). The WMAP team has answered many longstanding questions about the universe's age and composition.

    • 1 November 2007. Diverse Galaxies Lithograph. Image from the Hubble Space Telescope shows the diversity of galaxies in the universe. In addition to many elliptical and spiral galaxies, the image contains a few small irregular galaxies, and red, yellow, and blue foreground stars. An inquiry-based classroom activity accompanies the lithograph - both can be downloaded as PDF files from the Website.

    • 11 March 2007. Out There, By RICHARD PANEK, NY Times. Research by Saul Perlmutter, George Smoot (2006 Nobel Prize in Physics), and other groups over the last few years have started to destroy the general belief by astronomers that a simple model of the universe could explain most of the phenomena observed by astronomers. According to the latest observations, 96% of the mass of the universe is missing.

    • 18 April 2006. Update from Wilkinson Microwave Anisotropy Probe (WMAP) The satellite gathered data during three years of continuous observations of remnant afterglow light -- cosmic background radiation that lingers, much cooled, from the universe's energetic beginnings 13.7 billion years ago. WMAP data reveals that its contents include 4% atoms, the building blocks of stars and planets. Dark matter comprises 22% of the universe. This matter, different from atoms, does not emit or absorb light. It has only been detected indirectly by its gravity. 74% of the Universe, is composed of "dark energy", that acts as a sort of an anti-gravity. This energy, distinct from dark matter, is responsible for the present-day acceleration of the universal expansion.

    • 30 October 2002. Astronomers have discovered an ancient star near the center of our galaxy that may shed light on the universe's composition shortly after it was blasted into existence by the Big Bang. http://www.msnbc.com/news/828187.asp

    • 4 August 2001. By JAMES GLANZ, Exploring Cosmic Darkness, Scientists See Signs of Dawn -- discovery... amounts to a sighting of the first dawn in the cosmos as starlight and other radiation began to pervade the heavens... made by scientists with the Sloan Digital Sky Survey, an ambitious effort to map large swaths of the universe and catalog some 200 million celestial objects.

    • May-June 2001. T. Joseph W. Lazio, Razor-Sharp Radio Astronomy. Mercury Magazine. pp. 34-40. By constructing virtual telescopes the size of continents (and larger) radio astronomers are obtaining spectacular high resolution results.

    • 21 April 2001. FARTHEST SUPERNOVA EVER SEEN SHEDS LIGHT ON DARK UNIVERSEftp://ftp.hq.nasa.gov/pub/pao/pressrel/2001/01-058.txt -- NASA Release: 01-58

    • 20 August 2000. How Hipparchos data affects parallax measured distances (Dome-L posting)

    • 27 April 2000. Firming Up the Case for a Flat Cosmos-- BOOMERanG, a balloon-borne telescope mapped the microwave sky while circling Antarctica. Andrew Lange (Caltech) and Paolo de Bernardis (University of Rome La Sapienza, Italy) unveiled BOOMERanG's map of the far-southern microwave sky which shows minuscule variations in brightness (and hence temperature) of the all-pervasive microwave background, amounting to only a few hundredths of a percent.

    • Similar variations were revealed by the COBE satellite in the early 1990s, but COBE had very coarse vision, and couldnÕt resolve sky patches any smaller than about 7 degrees wide, the size the Big Dipper's bowl. BOOMERanG, by contrast, mapped details as small as a sixth of a degree of arc, or one-third the diameter of the full Moon. (From Sky & Telescope) March 2000. Sally Stephens, Hubble Warrior -- Wendy Freedman rests in the eye of the storm of the great Hubble constant debate. (Astronomy Magazine, pages 52-59.)

    • 17 December 1998. Accelerating Universe -- Accompanying Image (sn1998bu)

    • 8 October 1998. Hubble Deep Field Image -- http://oposite.stsci.edu/pubinfo/pr/1998/32/index.html -- galaxies could be over 12 billion light-years away (depending on cosmological models) making them the farthest objects ever seen.

Hardcopy Articles

    • Measuring the Astronomical Unit by Katherine Bracher. Mercury Magazine, Jan 2005. Excerpt: Fundamental to our estimates of the size of the Solar System is knowing how far away Earth is from the Sun. Last June's transit of Venus across the face of the Sun ... reminded many people of earlier expeditions t.... In 1761, 1769, 1874 and 1882 astronomers traveled to remote parts of the globe to take measurements of this rare phenomenon ... to measure the length of the Astronomical Unit or AU (the mean distance of Earth from the Sun). In ... January 1965, Brian G. Marsden described various techniques for determining this quantity...[In] the 3rd century BCE ...Aristarchus's idea was "to measure the angle between the sun and the moon when the latter appeared to be exactly half illuminated... [he] determined the angle to be 87', implying that the sun was 19 times more distant than the moon." ...One method for finding distances is to observe an object's parallax. ...One could in principle observe the Sun from different places on Earth, and use this method. But we cannot observe the Sun against a background of stars because it is too bright. Edmond Halley ... suggested... that this could be done "from observations of transits of Venus across the face of the sun."... measuring the position of Venus against the Sun from different terrestrial locations, .... in both the 1761 and 1769 transits, expeditions went to places like northern Canada, Siberia, St. Helena in the south Atlantic, and to Tahiti ... But the accuracy of determining the exact moment of beginning or end of the event was too poor to yield a good result. This was largely because of the illusion called the "black drop" effect, where "Venus appeared to attach itself to the sun by a long filament.... Marsden attributed this effect to the atmosphere of Venus. But later astronomers observed transits of Mercury, which has no atmosphere, and saw the same thing. It is now explained as an effect of blurring caused by a combination of the telescope and Earth's atmosphere. Astronomers then sought other nearby objects for which a parallax might be measurable, and by the 19th century several asteroids had been used in this way. In 1898 the asteroid Eros ... yielded a value for the AU of 149,670,000 km (plus or minus 20,000 km.) This was the best value until the advent of modern radar techniques. ... radio waves could be bounced off Venus; the length of time for the pulse to go and come back would yield the distance to Venus...Results from ...experiments in the early 1960s gave the AU as 149,598,000 km, plus or minus about 300 km. Currently the NASA website gives a value of 149,597,870.691 km.

    • The Universe as Seen by WMAP by John G. Cramer Alternate View Column Published in the October-2003 issue of Analog Science Fiction & Fact Magazine; This column is about the beginning of a new era of what is being called precision cosmology. It used to be a joke in the physics community that astrophysicists put the error bars in the exponent. In other words, they used numbers so poorly determined that they were unknown by several orders of magnitude. ... the Wilkinson Microwave Anisotropy Probe (WMAP) satellite, a joint initiative of Princeton University and NASA's Goddard Spaceflight Center, in its first year of operation has nailed down most of the constants of our universe to an accuracy of a few percent.

    • Hirshfeld, Alan W., The Race to Measure the Cosmos, Sky & Telescope magazine, November, 2001, p. 39.


    • Hirshfeld, Alan W., Parallax: The Race to Measure the Cosmos, W.H. Freeman and Co., 2001.

    • Webb, Stephen, Measuring the Universe: the Cosmological Distance Ladder, Springer-Verlag, 1999 -- How astronomers figured out how far away the planets, stars, and galaxies are. Aimed at undergraduates.