Next star past sun 4.23 light-years away

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For the next year we will look at questions readers often ask about the universe. One of the most frequent is: What are the closest and most distant objects from Earth outside the solar system?

The closest star to our own sun is Proxima Centauri that lies 4.23 light-years away. A light-year is the distance light travels in one year and equals about 5.9 trillion miles. The distance to Proxima Centauri was measured in 1915 by a technique called parallax. Even though Proxima Centauri is the closest star to us, it is still an immense distance away. If the sun were the size of the period at the end of this sentence, Proxima Centauri would be about 8 miles away. As great as this distance might seem, it is our backyard neighbor compared to the most distant object in the universe.

In 2004 Caltech astronomer Jean-Paul Kneib reported a galaxy 13 billion light-years away. The light started on its journey to Earth when the universe was only about 700 million years old as the universe is thought to be about 13.7 billion years old. Kneib used images obtained with the Hubble Space Telescope to determine the galaxy’s red shift. Galaxies recede from us faster the further away they are and this shifts their light reaching us to the red end of the visible spectrum. Thus a determination of the red shift gives a measure of the distance.

Also in 2004 the European Southern Observatory reported a galaxy at 13.25 billion light-years that would have made it the most distant object yet observed. The measurement recently was called into question and, to date, Kneib’s galaxy is the most distant object ever measured. The most distant object visible to the naked eye is the great Andromeda Galaxy, which is about 2 million light-years away. It appears as a faint and nebulous, or fuzzy, cloud in the constellation Andromeda.

Focus on the planets

Venus marks the advent of winter by passing from the evening to the morning sky in January. Note that in January the Milky Way crosses diagonally overhead from southeast to northwest.

Mercury appears low in the southeast during the morning twilight hours as the month opens. An unobscured horizon and clear atmospheric conditions will be needed to spot Mercury during its brief morning appearances.

Venus starts 2006 shining brightly low in the southwest an hour after sunset. It is joined by the thin crescent moon on New Year’s Day. By midmonth Venus passes into the morning sky disappearing until rising an hour before dawn at month’s end.

Mars is high in the south at dusk where it may be spotted as the bright reddish object just to the west of the Pleiades or Seven Sisters star cluster. Mars will remain in the evening sky during the winter months but gradually diminish in size and brightness.

Jupiter rises in the southeast about 3:00 a.m. on New Year’s Day and is well up on the horizon at dawn. Early risers who don’t mind the frigid temperatures will be rewarded with views of Jupiter’s equatorial belts and its four bright moons.

Saturn may be found well up in the south around 7 p.m. Saturn remains in view all night with its rings tilted towards us for excellent viewing. As an added bonus, the Beehive star cluster lies just above Saturn and in the same binocular field of vision.

Uranus, Neptune and Pluto are lost to viewing this month.

January events

1 Sunrise, 7:13 a.m.; sunset, 4:05 p.m. Moon at perigee, or closest approach to Earth, today. A thin crescent moon is to the left of Venus in the southwest at nightfall.

3 Tonight is the peak night for the Quadrantid meteor shower. This is a major shower, roughly 40 to 100 meteors per hour, radiating from the vicinity of Bootes the Herdsman. The near absence of the moon makes for ideal viewing conditions.

4 The Earth is at perihelion, or its closest approach to the sun for the year. We are 3.1 million miles closer to the sun than we will be at aphelion on July 3, 2006. So why is it colder in December than July?

6 Moon in first quarter, 1:56 p.m.

7 Saturn lies well up on the eastern horizon around 7 p.m. The two bright stars directly above the ringed planet are Castor and Pollux of Gemini while unmistakable Orion is situated to the upper right.

13 Besides being unlucky Friday the 13th, this is the day Venus passed from the evening into the morning sky.

14 Full moon, 4:47 a.m. The full moon of January is called the Old Moon, Wolf Moon, Ice Moon or the Moon After Yule.

17 Moon at apogee, or farthest distance from Earth, today.

19 The sun enters Capricornus on the ecliptic.

20 The sun enters the astrological sign of Aquarius but astronomically has just entered the sign of Capricornus.

22 Moon in last quarter, 10:14 a.m.

25 The crescent moon is paired with the red star Antares about an hour before sunrise. Jupiter is to the moon’s upper right.

28 Planet watchers with telescopes should check out Jupiter around 5 a.m. for a splendid view of its four major moons. Three – Io, Europa, and Callisto – are clustered to Jupiter’s lower left, and the fourth, Ganymede, is situated to its upper right.

29 New moon, 9:15 a.m.

30 Moon at perigee for the second time this month. This fact, combined with the recent new moon could lead to abnormally high tides.

31 Sunrise, 6:56 a.m.; sunset, 4:42 p.m.