May 25, 2018
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Age of oldest star has been remeasured

By Clair Wood, Special to the BDN

A star that has been known for more than a century because of its rapid movement across the heavens is now the oldest star ever discovered. When its age was first measured in 2000, it was found to be nearly 16 billion years old and created a problem, in that the universe was estimated to be only 13.8 billion.

“Either the cosmology, stellar physics, or the measurements is wrong,” said astronomer Howard Bond of the Space Telescope Science Institute. More refined measurements were made using such yardsticks as the oxygen/iron ratio and the absence of heavy metals in its composition. For example, the “Methuselah” star has only 1/250th of the heavy element content as the sun.

“We believe this star is the oldest known in the universe with such a well-determined age,” says Bond. The new figure for the star, which lies only 186 light years from Earth, is 14.5 billion years, plus or minus 0.8 billion years, which allows it to sneak in under the figure for the age of the universe. It must have formed within 600 million years of the Big Bang.

Focus on the planets

Only two planets, Jupiter and Saturn, are prominent in April skies. The lack of planets is offset by comet PanSTARRS, which will appear early in the month in the northwest about an hour after sunset. Not as bright as first anticipated, use binoculars to watch the comet’s course across the April sky.

Mercury appears fleetingly on the eastern horizon in early April as morning twilight deepens. On April 8, a waning crescent moon is to the upper left of the innermost planet.

Venus is lost in the sun’s glare for most of April but should reappear at the very end of the month very low in the west-northwest about 20 minutes after sunset.

Mars is lost in the glare of the sun and will not return until June.

Jupiter is the brightest point of light high in the west as darkness falls. Jupiter sets after midnight as April opens but is gone by 11 p.m. at month’s end. On April 13, look for the giant planet above a thin crescent moon. The four major moons of Jupiter continue to intrigue with their dance around and across the face of the planet.

Saturn rises in the east at sunset, is up all night, and sets in the southwest at dawn. The ring system has closed a little but is tilted enough to differentiate between the two ring systems with the dark Cassini Division between them. The major moon Titan is also easily spotted on its twice-monthly circuit of the planet.

Uranus is lost in the solar glare during April while Neptune may be barely visible above the southeast horizon in early twilight, where it resides among the stars of Aquarius.

April events

1 Sunrise, 6:17 a.m.; sunset, 7:02 p.m.

3 Moon in last quarter, 12:38 a.m.

10 New moon, 5:38 a.m.

13 Aldebaran, the “red eye” of the bull, is situated to the upper left of the crescent moon tonight with Jupiter shining above them.

15 The moon is at apogee, or farthest distance from Earth, today.

18 The moon is at first quarter, 8:31 a.m. The sun enters Aries on the ecliptic.

19 The sun enters the astrological sign of Taurus but astronomically has just entered Aries.

22 This should be a peak night for the Lyrid meteor shower but a bright gibbous moon will wash out all but the brightest of them. The normal 20 meteors per hour will be halved and the best time to see these will be in a narrow window of time between the setting of the moon and dawn.

24 Spica, the bright star of Virgo, is above and near to the nearly full moon in the southeast an hour after sunset.

25 Full moon, 3:59 p.m. The full moon of April is known as the Pink Moon, Egg Moon or Grass Moon. Note that Saturn is prominent to the upper left of the moon tonight.

27 The moon is at perigee, or nearest approach to Earth, today.

28 The bright orange star beneath the moon during the predawn hours is Antares of Scorpio.

30 Sunrise, 5:27 a.m.; sunset, 7:39 p.m.

Send astronomical queries to Clair Wood at or care of the Bangor Daily News, Style Desk, P.O. Box 1329, Bangor 04402.


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