Hubble Space Telescope image of spiral galaxy NGC 4603. It is the most distant galaxy with Cepheids used to measure the Hubble Constant.
Click on image for full size
Scientists Find the True Hubble Constant!
News story originally written on May 26, 1999
After eight long years, the Hubble Space Telescope Key Project Team finally revealed what they believe is the real Hubble Constant. The Hubble Constant is the speed which the Universe is expanding at. For over 70 years, scientists have argued over the exact number.
Astronomers are able to use the constant to "work backwards", in order to find the age of the Universe. Now that the Hubble team has found Hubble's Constant to be 70 kilometers per second per megaparsec, they have determined the age of the Universe to be 12 billion years old. At one time, scientists differed on the value of the constant by a factor of 2. Now, the constant has been measured with an error of only 10 percent.
The Hubble team used a certain type of star called a Cepheid variable star. A Cepheid is a special pulsating star that can be used to make precise distance measurements. Over 800 Cepheids were found during the 10 year project.
Finding the Hubble Constant was one of three original goals set by astronomers when the telescope was first launched in 1990. The telescope is named after Edwin Hubble, the first to believe the Universe is expanding.
Shop Windows to the Universe Science Store!
Our online store
on science education, classroom activities in The Earth Scientist
specimens, and educational games
You might also be interested in:
The Hubble Space Telescope (HST) was one of the most important exploration tools of the past two decades, and will continue to serve as a great resource well into the new millennium. The HST found numerous...more
It was another exciting and frustrating year for the space science program. It seemed that every step forward led to one backwards. Either way, NASA led the way to a great century of discovery. Unfortunately,...more
Scientists found an ancient galaxy that may be one of the first ever! The galaxy is hidden inside an enormous black hole. This black hole is estimated at 100 million times the mass of our Sun. The galaxy...more
The Space Shuttle Discovery lifted off from Kennedy Space Center on October 29th at 2:19 p.m. EST. The weather was great as Discovery took 8 1/2 minutes to reach orbit. This was the United States' 123rd...more
A moon was discovered orbiting the asteroid, Eugenia. This is only the second time in history that a satellite has been seen circling an asteroid. A special mirror allowed scientists to find the moon...more
Will Russia ever put the service module for the International Space Station in space? NASA officials want an answer from the Russian government. The necessary service module is currently waiting to be...more
A coronal mass ejection (CME) happened on the Sun early last month. The material that was thrown out from this explosion passed the ACE spacecraft. The SWICS instrument on ACE has produced a new and very...more