蜜桃恋人

10 Facts About Vega, Summer's Bright Star

Caption

Image Credit & Copyright: Steed Yu & 

Subhead

Look for the Bright Star Vega in July!

No content available.

In early summer, night falls at its latest hour鈥攁round 9:30 to 10 PM. High in the east shines summer鈥檚 bright star鈥攖he famous Vega. Learn fascinating facts about Vega, a favorite of stargazers and astronomers, and its fascinating folklore.

Away from city lights in mid-July, one could see as many as 2,500 naked-eye stars. But if you look east, only one star stands out because it鈥檚 the only bright star overhead鈥擵ega.   

1. Vega of The Summer Triangle

Vega is the 5th brightest star visible from Earth, and the 3rd brightest easily visible from mid-northern latitudes, after Sirius and the Arcturus. In the northern sky, it鈥檚 2nd brightest after the red giant, Arcturus.

Vega is also one of three stars in the famous star pattern called the Summer Triangle, along with Deneb and Altair. 


Learn more about the Summer Triangle.

2. Look Straight Up in July

Its high-up perch is a mere springboard. For those who live near latitude 40掳 (such as residents of Boston, New York, Denver, Philly, Indianapolis, or San Francisco), Vega is uniquely the only bright star that ascends to within a few degrees of the exact zenith. Straight up. On these summer nights, that happens at 1 AM. Or you can patiently wait for late September, when Vega hovers directly overhead at nightfall.


Vega, the Harp Star. Credit:  by Stephen Rahn via .

3. How to Pronounce Vega

Most summer stars are dim and cursed with designations like HDE224334 or Zubeneschamali. Only a handful are brilliant and have popular names. Boasting the shortest name of any brilliant star, Vega is nonetheless routinely mispronounced as VAY-ga. That鈥檚 because few know this phonetics tip: star names are simple transliterations from their original language. They should be spoken as spelled. Orion鈥檚 brilliant foot is Rigel, pronounced RYE鈥榡l and Vega is really VEE-guh. No need to add a latin twist with VAY-ga and make it into a cigar or a Chevy. Originally it was WEE-ga, coming from an old Arabic word meaning a falling eagle. Indeed, in my antique astronomy books from the 18th century, the star is listed as Wega.

4. A Vegetarian Star?

People who eschew all animal foods call themselves Vegans, a term probably coined in the 1940s. But their ancestors were not Vegans who hailed from Vega, with its non-vegetarian 鈥渆agle鈥 name. Despite being encircled by a dusty disk whose infrared signature has been interpreted as evidence of a planetary system, actual life is implausible there because of the star鈥檚 youth.

5. Vega Folklore

Interestingly, there鈥檚 a story about Vega and Altair. A number of Asian cultures have folklore surrounding these two stars, which is often some variation of the following: A celestial goddess falls in love with a mere mortal, but the goddess鈥 father forbids their union and it is doomed. However, the gods take pity and place the two lovers in the sky as Vega and Altair. Separated by a celestial river, the Milky Way, these star-crossed lovers are only allowed to reunite once year. They cross a bridge of magpies across the Milky Way on the 7th night of the 7th Moon.

Vega is also called the Harp Star since it鈥檚 in the constellation of Lyra, the Harp. According to Greek myth, the musician Orpheus played the harp to entrance both god and moral.

vega-folklore.jpg

6. Vega is How We Measure Brightness

Shining at a steady magnitude zero, Vega serves as the 鈥渟tandard candle鈥 used by the worldwide astronomical community to calibrate the brightness of everything else in the universe. Like the French bar of platinum that defined the meter until recently, Vega is the sky鈥檚 reference point for the magnitude system.

It鈥檚 an ideal choice because it displays not the slightest flickering or unsteady habit; it鈥檚 also a single star like our Sun, instead of a binary like most. Its brilliance, equal to 58 suns, emanates from a dazzling 2.7 million-mile-in-diameter ball with a surface of nearly pure hydrogen, floating at the relatively nearby perch of 25 lightyears.

7. Why is Vega So Bright? 

Vega is more than 40 times brighter than our Sun! It鈥檚 twice the size and mass of the Sun. And it鈥檚 fairly close to Earth (for a star)鈥攋ust 25 light-years away. Its nearness is the main reason why Vega is so bright.

8. Why is Vega Blue? 

Why is Vega blueish in color? Its surface temperature is nearly 17,000 degrees Fahrenheit, making it about 7,000 degrees hotter than our Sun.

9. The North Star of Past and Future

Vega is not as normal as we once thought. In 1994, a team of Canadian astronomers announced that Vega has unsuspected peculiarities. It spins much faster than anyone imagined, in a giddy 11 hours compared to 25 days for our own Sun. And its pole of rotation is pointed straight toward us, give or take five degrees. For any Vegans looking skyward, our Sun is its north star!

Twelve thousand years from now, we鈥檒l return the favor. Vega periodically becomes our own pole star as Earth鈥檚 axis wobbles through its 26-millennium precession. Brightest of all north stars through the eons, it nonetheless misses the celestial pole by four degrees, making it nearly ten times less precise than the current one, Polaris.

10. Earth is Traveling Towards Vega!

As if this weren鈥檛 enough to keep us interested, Vega marks the approximate direction toward which we travel in space. As our entire starry neighborhood participates in the galaxy鈥檚 grand rotation, we do a little nine mile-per-second sideslip in Vega鈥檚 direction. Those who mistakenly think that the whole universe races away from us might take a glance overhead. In a cosmos where the redshift is as common as pizza, this diamond at the zenith displays the much rarer blueshift.

So enjoy Vega right now as it hovers overhead near the zenith. But no need to rush. Vega will only grow brighter as it heads our way, keeping our descendants company through the eons.

鈫 See our Star Map with Vega and the Summer Triangle.

About The Author

Bob Berman

Bob Berman, astronomer editor for The Old Farmer鈥檚 蜜桃恋人, covers everything under the Sun (and Moon)! Bob is the world鈥檚 most widely read astronomer and has written ten popular books. Read More from Bob Berman
 

No content available.