Featured Research

from universities, journals, and other organizations

Hubble Completes Eight-Year Effort To Measure Expanding Universe

Date:
May 26, 1999
Source:
Space Telescope Science Institute
Summary:
The Hubble Space Telescope Key Project team today announced that it has completed efforts to measure precise distances to far-flung galaxies, an essential ingredient needed to determine the age, size and fate of the universe.

The Hubble Space Telescope Key Project team has announced that it hascompleted efforts to measure precise distances to far-flung galaxies, anessential ingredient needed to determine the age, size and fate of theuniverse.

"Before Hubble, astronomers could not decide if the universe was 10billion or 20 billion years old. The size scale of the universe had arange so vast that it didn't allow astronomers to confront with anycertainty many of the most basic questions about the origin andeventual fate of the cosmos," said team leader Wendy Freedman, of theObservatories of the Carnegie Institution of Washington. "After allthese years, we are finally entering an era of precision cosmology.Now we can more reliably address the broader picture of the universe'sorigin, evolution and destiny."

The team's precise measurements are the key to learning about theexpansion rate of the universe, called the Hubble constant. Measuringthe Hubble constant was one of the three major goals for NASA's HubbleSpace Telescope before it was launched in 1990.

For the past 70 years astronomers have sought a precise measurement ofthe Hubble constant, ever since astronomer Edwin Hubble realized thatgalaxies were rushing away from each other at a rate proportional totheir distance, i.e. the farther away, the faster the recession. Formany years, right up until the launch of the Hubble telescope - therange of measured values for the expansion rate was from 50 to 100kilometers per second per megaparsec (a megaparsec, or mpc, is 3.26million light-years).

The team measured Hubble's constant at 70 km/sec/mpc, with anuncertainty of 10 percent. This means that a galaxy appears to bemoving 160,000 miles per hour faster for every 3.3 million light-years awayfrom Earth.

"The truth is out there, and we will find it," said Dr. Robert Kirshner,of Harvard University. "We used to disagree by a factor of 2; now we arejust as passionate about 10 percent. A factor of two is like beingunsure if you have one foot or two. Ten percent is like arguing aboutone toe. It's a big step forward."

Added Dr. Robert Kennicutt of the University of Arizona, a co-leader ofthe team: "Things are beginning to add up. The factor of two controversyis over."

The team used the Hubble telescope to observe 18 galaxies out to 65million light-years. They discovered almost 800 Cepheid variable stars,a special class of pulsating star used for accurate distancemeasurement. Although Cepheids are rare, they provide a very reliable"standard candle" for estimating intergalactic distances. The team usedthe stars to calibrate many different methods for measuring distances.

"Our results are a legacy from Hubble telescope that will be used in avariety of future research," said Dr. Jeremy Mould, of the AustralianNational University, also a co-leader of the team. "It's exciting to seethe different methods of measuring galaxy distances converge, calibratedby the Hubble Space Telescope."

Combining the Hubble constant measurement with estimates for the densityof the universe, the team determined that the universe is approximately12 billion years old - similar to the oldest stars. This discoveryclears up a nagging paradox that arose from previous age estimates. Theresearchers emphasize that the age estimate holds true if the universeis below the so-called "critical density" where it is delicatelybalanced between expanding forever or collapsing. Or, the universe ispervaded by a mysterious force pushing the galaxies farther apart, inwhich case the Hubble measurements point to an even older universe.

The universe's age is calculated using the expansion rate from precisedistance measurements, and the calculated age is refined based onwhether the universe appears to be accelerating or decelerating, giventhe amount of matter observed in space. A rapid expansion rate indicatesthe universe did not require as much time to reach its present size, andso it is younger than if it were expanding more slowly.

The Hubble Space Telescope Key Project team is an international group of27 astronomers from 13 different U.S. and international institutions.The Space Telescope Science Institute is operated by the Association ofUniversities for Research in Astronomy, Inc. for NASA, under contractwith NASA's Goddard Space Flight Center in Greenbelt, MD.

- end -

NOTE TO EDITORS: Image files, captions, illustrations and animations are

available at:http://oposite.stsci.edu/pubinfo/pr/1999/19 and via links inhttp://oposite.stsci.edu/pubinfo/latest andhttp://oposite.stsci.edu/pubinfo/pictures

Higher resolution (300 dpi JPEG and TIFF) image files are available athttp://oposite.stsci.edu/pubinfo/pr/1999/19/extra-photos.html


Story Source:

The above story is based on materials provided by Space Telescope Science Institute. Note: Materials may be edited for content and length.


Cite This Page:

Space Telescope Science Institute. "Hubble Completes Eight-Year Effort To Measure Expanding Universe." ScienceDaily. ScienceDaily, 26 May 1999. <www.sciencedaily.com/releases/1999/05/990526061527.htm>.
Space Telescope Science Institute. (1999, May 26). Hubble Completes Eight-Year Effort To Measure Expanding Universe. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/1999/05/990526061527.htm
Space Telescope Science Institute. "Hubble Completes Eight-Year Effort To Measure Expanding Universe." ScienceDaily. www.sciencedaily.com/releases/1999/05/990526061527.htm (accessed October 23, 2014).

Share This



More Space & Time News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Russian Cosmonauts Kick Off Final Spacewalk of 2014

Russian Cosmonauts Kick Off Final Spacewalk of 2014

Reuters - US Online Video (Oct. 22, 2014) — Russian cosmonauts Maxim Suraev and Alexander Samokutyaev step outside the International Space Station to perform work on the exterior of the station's Russian module. Rough Cut (no reporter narration) Video provided by Reuters
Powered by NewsLook.com
Comet Siding Spring Grazes Mars' Atmosphere

Comet Siding Spring Grazes Mars' Atmosphere

Newsy (Oct. 19, 2014) — A comet from the farthest reaches of the solar system passed extremely close to Mars this weekend, giving astronomers a rare opportunity to study it. Video provided by Newsy
Powered by NewsLook.com
Latin America Launches Communications Satellite

Latin America Launches Communications Satellite

AFP (Oct. 17, 2014) — Argentina launches a home-built satellite, a first for Latin America. It will ride a French-made Ariane 5 rocket into orbit, and will provide cell phone, digital TV, Internet and data services to the lower half of South America. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
This Week @ NASA, October 17, 2014

This Week @ NASA, October 17, 2014

NASA (Oct. 17, 2014) — Power spacewalk, MAVEN’s “First Light”, Hubble finds extremely distant galaxy and more... Video provided by NASA
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins