Fellow from observatory helps club see how age of universe is being measured

SIERRA VISTA — Members of the Huachuca Astronomy Club are used to looking at stars, but figuring out the age of the universe from stars was the focus on Friday.

Lucas Macri has researched that question as a Hubble and Goldberg post-doctoral fellow at the National Optical Astronomy Observatory in Tucson for the past five years.  Macri spoke at the club’s meeting about one of the key projects of the Hubble Space Telescope — measuring the expansion rate of the universe, or Hubble Constant, to determine the age of the Universe.

The universe is estimated to be about 14 billion years old, give or take 2 billion years, Macri said.

His work and others has dealt with measuring Cephid variables, or stars that display a “saw tooth pattern” of brightness, that have a distinct rise and decline over a fixed period of days, Macri said.

The measurements can be used to measure the relative distances between galaxies.

To determine the age of the universe an “anchor galaxy” with a known distance is needed first for an accurate measurement of the expanding universe.

“The problem with the galaxies we can see with Hubble, is they’re still close to us,” Macri said, which affects the accuracy of the measurements.

NGC 4258, a spiral galaxy with a black hole positioned at a 90-degree angle to the sun was used as the anchor galaxy for Macri and other researchers’ measurements.

The anchor galaxy is then compared to the brightness and rotation of a galaxy further away, and a distance between the two can be determined.

The recent discovery of “dark energy,” which is estimated to compose of about 73 percent of the universe, about five years ago, drives astronomers’ quest for a more accurate measurement of the age of the universe, Macri said.

In 2004 a fuse on the Hubble’s camera went out, though the research was continued with the use of the Gemini North Telescope in Hawaii, Macri said.

The Hubble Space Telescope will be repaired next year, and Macri expects that the age of the universe will be known to 3 percent accuracy within three years.

Neal Galt, better known as the “Backyard Astronomer” from his column in the Herald/Review, also spoke at the clubs meeting and presented a slide show of pictures of formations on the moon, including volcanic dunes, ghost craters and swamps.

“You didn’t know the moon had swamps, did you?” Galt asked.

Galt also spoke about the planets that are currently visible in the night sky, including Mercury, Venus and Saturn.

“Jupiter reigns in the southeast by the time the sun sets. It’s a great time to see Jupiter with a telescope,” he said.

Bob Kepple and Glen Sanner also spoke about dark nebulas, clouds of interstellar dust that can be viewed silhouetted against the Milky Way and other sources of light.

They’re best viewed with a low-powered telescope, Sanner said.

Kepple showed several slides of his favorite dark nebulas, including the “Great Rift,” which can be seen against the Milky Way with the naked-eye, the Pipe nebula, which derives its name from it’s shape, and the Ink Spot nebula.

“It has a triangular shape that’s very distinguishing,” Kepple said.

Club president Wayne Johnson said about 50 people attended the monthly meeting. The group also holds star parties and workshops for the public.

Next month, Jay Holberg will speak to the club about the star Sirius, also known as the “dog star.”

Other club events open to the public can be found on the group’s Web site at www.hacastronomy.com.

REPORTER Laura Ory can be reached at 515-4683 or by e-mail at laura.ory@svherald.com.