Brightest Stars

Elnath is a bright star close to the galactic anticenter

Sky chart: constellation Taurus with Elnath and other stars labeled, and the galactic anticenter marked.
The galactic anticenter lies about 3 degrees to the east of the star Elnath, or Beta Tauri. Elnath is the 2nd brightest star in the constellation Taurus the Bull.

On August evenings, we look toward the center of our Milky Way galaxy. And in January and February, we do the opposite. We look opposite the galaxy’s center, toward the galactic anticenter and the galaxy’s nearest outer edge. The star Elnath (aka Beta Tauri, and sometimes called Alnath) in the constellation Taurus the Bull is the closest bright star on our sky’s dome to the galactic anticenter.

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How to find Taurus’ 2nd brightest star

Elnath is easy to find if you learn to recognize the Face of the Bull in the constellation Taurus. The Face of the Bull in Taurus is shaped like the letter V. The V-shape is fairly easy to pick out from the background stars. These stars are members of the Hyades Cluster. By mid-January, you can find the V-shape nearly overhead about three hours after sunset. This V-shape includes the brightest star in Taurus, red Aldebaran.

If you extend the right side of the letter V (the side that’s opposite Aldebaran), you come to the star Elnath. Elnath represents the Northern Horn of Taurus the Bull. It’s the 2nd-brightest star in Taurus after Aldebaran, which represents the Bull’s bloodshot eye.

So, Elnath isn’t quite as bright as Aldebaran. But it’s also part of a noticeable pattern, and it’s blue-white in color.

Use Orion to find Taurus and Elnath

Can’t find the Face of the Bull? Try finding Orion the Hunter first, an extremely prominent constellation. You can recognize Orion for its Belt, a short, straight row of three medium-bright stars.

Draw a line upward through Orion’s Belt to find Aldebaran and the V-shape group of stars outlining the Bull’s Face. Extend the lines off the top of the V to locate the two stars marking the tips of the Bull’s horns. The northern and brighter horn star is Elnath.

Starry sky dotted with brighter stars: Orion, Taurus, Pleiades, over rocky horizon, with red Mars.
View at EarthSky Community Photos. | Miguel Ventura in Fafe, Portugal, captured this image on August 28, 2022. Thank you, Miguel! You can see Orion near the horizon. Above it is the V-shape of the Hyades and its bright star Aldebaran in Taurus. The bright bluish star far to the left is Elnath, with the galactic anticenter nearby. Above the Hyades, Miguel captured bright, orangish Mars as it visited Taurus. And near the top we see the Pleiades star cluster.

When and where to look for Elnath

In the Northern Hemisphere, we see Taurus and its stars on winter evenings. Elnath stands opposite the sun around mid-December and thus rises around sunset and sets around sunrise. In January and February, Elnath is already up in the southeast at sunset. By June, Elnath will be lost to the sun’s glare and won’t be seen at all. Excepting June, however, you can see Elnath for at least part of the night throughout the year.

Elnath stands a bit north of the ecliptic, the annual pathway of the sun in front of the background stars. Because the moon’s path is always near the ecliptic, the moon swings close to Elnath every month. Generally, the moon swings to the south of Elnath. On occasion, the moon swings far enough north that it occults – passes directly in front of – Elnath. We are currently in the midst of a series of occultations that will last until April 11, 2027.

How to locate the Milky Way’s anticenter

The galactic anticenter lies about 3 degrees to the east of the star Elnath. Three degrees is about the amount of sky that your thumb covers when held at arm’s length. The galactic anticenter isn’t a place, it’s just a direction in the sky from our perspective on Earth. Elnath is about 130 light-years away, whereas the outskirts of our galaxy’s disk are many thousands of light-years away. So Elnath is much closer and just shows the direction.

While the closest bright star to the galactic anticenter is Elnath in Taurus, the anticenter isn’t in Taurus. Instead, it lies in a neighboring constellation, Auriga the Charioteer.

Complex graphic showing a galaxy with Earth on the far side of the sun from the galactic center, with view outward.
This graphic shows you a top-down view, looking at the location of the sun inside the galaxy. At this season, the galactic center is behind the sun, and Earth’s nighttime side points toward the galactic anticenter. When we look opposite the center of the galaxy, we are looking toward the anticenter. Image via ESA/ Hubble/ Gaia/ DPAC.

Science of the star Elnath

Elnath sparkles white and is tinged in blue. This star’s color indicates that it has a hot surface temperature of about 13,600 Kelvin (13,300 Celsius or 24,000 Fahrenheit). Contrast this to the surface temperature of our yellow-colored sun, which is 5,800 Kelvin (5,500 C or 10,000 F).

According to the star expert Jim Kaler, Elnath has 4.5 times the sun’s mass and shines with the firepower of 700 suns.

Elnath’s position is RA: 5h 26m 17.5s, dec: +28° 36′ 27″

Bottom line: The galactic anticenter is the position opposite the Milky Way’s center from our viewpoint on Earth. If you want to look toward the anticenter, gaze toward Elnath. This star is the 2nd-brightest star in the constellation Taurus the Bull and is just 3 degrees from the galactic anticenter, which lies nearby in the constellation Auriga.

Posted 
January 15, 2024
 in 
Brightest Stars

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