Virgo is a zodiac constellation associated with goddesses of justice, agriculture and prophecy. The constellation is often depicted with angel-like wings and an ear of wheat in her left hand.
To find Virgo in the evening sky, planetarium director Jean Creighton suggests using the nemonic “arc to Arcturus” (draw an arc from the handle of the Big Dipper). Then extend that line to spy Spica, Virgo’s brightest star.
Arc to Arcturus
The bright orange star Arcturus is the fourth-brightest star in our night sky and can be seen from the northern hemisphere. It is also one of the stars in the Virgo constellation, which takes up 1294 square degrees of the night sky and can be seen by observers north of 50 degrees south latitude.
The stars of the Virgo constellation form an asterism known as the Spring Triangle. It is comprised of the three alpha-type stars Arcturus, Spica and Regulus. These three stars are also referred to as the “Big Dipper’s Stars.”
Arcturus is a red giant star (spectral type K0 III) that is about 36.7 light years from Earth, making it about a half million years younger than our Sun. It is currently traveling in our direction and will approach us in about 4,000 years.
Astronomers believe that Arcturus may be a satellite of the Milky Way galaxy. This is based on its high proper motion, which was discovered by Sir Edmond Halley in 1718. This motion is a result of the fact that our Milky Way galaxy was once part of another large galaxy and that the two galaxies are now merging.
As the fourth-brightest star in the sky, it is also one of the easiest to locate. To locate the star, look up at the Big Dipper asterism and follow the arc of the handle until you reach a bright orange star.
Once you have located the star, use your astronomical knowledge to identify its position and spectral classification. Freshman astronomy students learn the proper order for the spectral classification of stars with a mnemonic that goes like this: “Arc to Arcturus, speed on to Spica”.
In addition to being easy to locate, Arcturus is also very easy to distinguish from other bright stars. Its isolation from the nearby bright stars helps to make it so easy to see.
It has the lowest metallicity of any star in our solar system, meaning that it is very dense and dominated by iron, but it has a higher ratio of alpha-elements than the Sun. As a result, Arcturus is likely a Population II star, a type of star that formed in the early days of our galaxy.
Arc to Spica
Spica is one of the brightest stars in the constellation Virgo. It sits within the ecliptic, an imaginary line on the sky that represents the path of the Sun, moon, and planets throughout the year. The moon can occult (eclipse) Spica from time to time, and it’s worth watching for these events when you’re out looking at the stars.
Virgo is the second-largest zodiac constellation, and it can be found in the eastern part of the night sky between Leo to the west and Libra to the east. It’s also the third-largest constellation in total area, covering 1,294 square degrees of the sky, behind Hydra and Ursa Minor.
It is one of the 12 zodiac constellations first cataloged by Ptolemy in the 2nd century CE. The zodiac is a set of thirteen constellations that mark the paths the Sun travels across the sky during the course of a year, and the September equinox is located in Virgo.
In addition to being the brightest star in Virgo, Spica is one of the brightest stars overall in the entire night sky. It’s a blue subgiant star, about 250 light-years from Earth. It’s a Beta Cephei type variable star, meaning that it pulsates its surface causing changes in brightness.
Another interesting thing about Spica is that it’s a spectroscopic binary, which means that it has at least two stars orbiting close together. As the stars orbit each other, they distort each other into egg-shaped shapes and cause slight changes in their apparent diameter.
These changes in their size are referred to as Doppler shifts, and they’re what led astronomers to believe that there was a second star in this system back in 1890.
It’s not uncommon for some spectroscopic binary stars to have several other stars in their system, so if you do see Spica with your naked eye, it’s likely that there’s more to the story than just a single star. Some astronomers think that there may be as many as three other stars in this system, making it a quintuple star.
Arc to Vindematrix
Virgo is one of the largest constellations, and it stretches across 1294 square degrees of the sky. It is located in the third quadrant of the Southern Hemisphere (SQ3) and can be seen at latitudes between +80° and -80°, depending on your location.
This constellation is also one of the original 48 constellations, first catalogued by Ptolemy in the 2nd century CE. Its name translates to “the virgin,” and it has been associated with goddesses of virtue since ancient times. During the Middle Ages, it was often seen as a female figure with a head and shoulders, marked by Porrima and Zaniah, and her arms, with Vindemiatrix, her “ear of wheat.”
Spica is a bright star in Virgo that shines blue-white and can be easily found using a good pair of binoculars or a telescope. This star is the 16th brightest in the night sky and was discovered spectroscopically in 1890.
A double star, Porrima, is another bright star in Virgo and marks the center of the constellation’s Y-shaped pattern. This star has a magnitude of 2.74 and is relatively close to Spica, making it easy to spot.
Virgo’s other bright stars include Elgafar, Flegetonte, Heze, Kang, Khambalia, Lich, Malmok, Minelauva, Monch, Porrima, Syrma, Vindemiatrix, and Zaniah. There are also 20 known planets in Virgo, more than any other constellation.
There are also a few bright galaxies in the constellation, including Messier 49 and 58. The best time to observe these galaxies is in the spring or early fall.
The Virgo Cluster, which contains many galaxies, lies 5deg to 10deg west of e Vir (Vindemiatrix). It is a rich galaxy cluster that is visible with most telescopes and can be observed throughout the year.
It is possible to see the Virgo Cluster with a simple pair of binoculars, but a small telescope will reveal much more detail. It is important to note that the Virgo Cluster is in a region of the sky that is not well-served by moonlight or other light pollution, so observing it requires good dark skies.
The best time to view this constellation is during the spring or early autumn, when most of its stars are at their brightest and the Milky Way is near its brightest. The constellation is also home to a few interesting deep sky objects, such as the quasar 3C 273.
Arc to Denebola
Denebola is one of the brightest stars in the constellation Leo. It is a white A-type main sequence star with an apparent visual magnitude of 2.14 and is located 36 light-years from Earth. It is also a Delta Scuti variable star, which shows slight variations in brightness due to radial pulsations.
Its pulsation can be seen in astroimages. It is a very young star, and it is thought to be less than 400 million years old. It is much more massive than our Sun, and it is 15 times more luminous.
The star is a Delta Scuti variable, meaning that its luminosity varies slightly over a period of hours. These pulsations are not noticeable to the naked eye, but they can be detected by using a telescope or astronomical camera.
Another interesting fact about this star is that it has a circumstellar debris disk in orbit around it. This is not common among stars, but it is considered to be an important factor in determining the possibility of extrasolar planet formation.
If you look carefully at the sky, you will see that Denebola forms a nearly equilateral triangle with Arcturus and Spica. These three stars form the so-called “Spring Triangle” asterism in the Northern Hemisphere.
To find Denebola, you should follow the arc of the Big Dipper to Arcturus and spike across the sky to Spica (Alpha Virginis). Then follow that arc up and to the right to Denebola, which is the second brightest star in Leo behind Regulus.
This star is also part of the Great Diamond asterism. It forms with the bright stars Arcturus, Spica, and Cor Caroli, and is easily visible with binoculars or a small telescope at night.
Denebola is located about 36.2 light-years from the Sun. It is an A-type main sequence star with 75% more mass than the Sun and 15 times more luminous. It is a Delta Scuti variable, which means that its luminosity varies very slightly over a period of a few hours.
Despite its age, Denebola is a relatively young star and it has a circumstellar dust disk in orbit around it. This disk is thought to be similar to that of Vega, which was once the brightest star in the Milky Way before it exploded. The disk was formed when Denebola was only 400 million years old.