Astronomy science – Time to know about Stars
In the night sky, tiny bright objects are seen which are twinkling the sky. Stars are made of hydrogen, a smaller amount of helium, and trace amounts of other elements. Even the most abundant others elements present in stars (oxygen, carbon, neon, and nitrogen) are only present in very small quantities.
Space is definitely not empty it is full of gas and dust. Many stars have their own systems of planets, moons, asteroids, and comets. Thermonuclear fusion Is the process in which a star produces its light, heat, and energy. Towards the end of the twentieth century, astronomers began to discover planets orbiting other stars. Because planets are so much smaller and fainter than stars, they are difficult to detect and impossible to see.
Types of Stars
There are many different types of stars. Stars that are in their main sequence (normal stars) are categorized by their colour. The smallest stars are red and don’t give off much of a glow. Medium size stars are yellow, like the Sun. The largest stars are blue and are hugely bright. The larger the main sequence star, the hotter and brighter they are.
Dwarfs– Smaller stars are called dwarf stars. Red and yellow stars are generally called dwarfs. A brown dwarf is one that never quite got large enough for nuclear fusion to occur. A white dwarf is the remnants of the collapse of a red giant star.
Giants – Giant stars may be main sequence stars like a blue giant, or stars that are expanding like red giants. Some supergiant stars are as big as the entire Solar System!
Neutrons – A neutron star is created from the collapse of a giant star. It’s very tiny, but very dense.
Here are the ten brightest stars in Earth’s night sky. These make excellent stargazing targets from all but the most light-polluted cities.
Sirius, also known as th e Dog Star, is the brightest star in the night sky. Its name comes from the Greek word for “scorching.” Many early cultures had names for it, and it had special meanings in terms of rituals and the deities they saw in the sky.
It’s actually a double star system, with a very bright primary and a dimmer secondary star. Sirius is visible from late August (in the early mornings) until mid-to-late March) and lies 8.6 light-years away from us.
Canopus was well known to the ancients and is named either for an ancient city in northern Egypt or the helmsman for Menelaus, a mythological king of Sparta. It’s the second brightest star in the night sky, and mainly visible from the Southern Hemisphere. Observers who live in the southern regions of the Northern Hemisphere can also see it low in their skies during certain parts of the year.
Canopus lies 74 light-years away from us and forms part of the constellation Carina. Astronomers classify it as a type F star, which means it’s slightly hotter and more massive than the Sun. It’s also a more aged star than our Sun.
Rigel Kentaurus, also known as ALpha centurai, is the third brightest star in the night sky. Its name literally means “foot of the centaur” and comes from the term “Rijl al-Qanṭūris” in Arabic. It’s one of the most famous stars in the sky, and first-time travelers to the Southern Hemisphere are often eager to view it.
Rigel Kentaurus is not just one star. It’s actually part of a three-star system, with each star looping around with the others in an intricate dance. It lies 4.3 light-years away from us and is part of the constellation Centaurus. Astronomers classify Rigel Kentaurus as a type G2V star, similar to the Sun’s classification. It may be about the same age as our Sun and is in roughly the same evolutionary period in its life.
Arcturus is the brightest star in the northern-hemisphere constellation Boötes. The name means “Guardian of the Bear” and comes from ancient Greek legends. Stargazers often learn it as thet star-hop from the stars of the Big Dipper to find other stars in the sky. There’s an easy way to remember it: simply use the curve of the Big Dipper’s handle to “arc to Arcturus.”
This is the 4th-brightest star in our sky and lies just around 34 light-years away from the Sun. Astronomers classify it as a type K5 star which, among other things, means it is slightly cooler and a bit older than the Sun.
Vega is the fifth-brightest star in the night sky. Its name means “the swooping eagle” in Arabic. Vega is about 25 light-years from Earth and is a Type A star, meaning it is hotter and somewhat younger than the Sun.
Astronomers have found a disk of material around it, which could possibly hold planets. Stragzers know
Vega as part of the constellation Lyra, the Harp. which rides through the Northern Hemisphere skies from early summer to late autumn.
The sixth brightest star in the sky is Capella. Its name means “little she-goat” in Latin, and it was charted by many ancient cultures, including the Greeks, Egyptians, and others.
Capella is a yellow giant star, like our own Sun, but much larger. Astronomers classify it as a type G5 and know that it lies some 41 light-years away from the Sun. Capella is the brightest star in the constellation Auriga, and is one of the five bright stars in an asterism called the “Winter Hexagon”.
Rigel is an interesting star that has a slightly dimmer companion star that can be easily seen through telescopes. It lies about 860 light-years away but is so luminous that it’s the seventh-brightest star in our sky.
Rigel’s name comes from the Arabic word for “foot” and it is indeed one of the feet of the conselltation, Orion, Hunter . Astronomers classify Rigel as a Type B8 and have discovered it is part of a four-star system. It, too, is part of the Winter Hexagon and is visible from October through March each year.
Procyon is the eighth brightest star night sky and, at 11.4 light-years, is one of the closer stars to the Sun. It’s classified as a Type F5 star, which means it’s slightly cooler than the Sun. The name “Procyon” is based on the Greek word “prokyon” for “before the Dog” and indicates that Procyon rises before Sirius (the dog star). Procyon is a yellow-white star in the constellation Canis Minor and is also part of the Winter Hexagon. It’s visible from most parts of both the northern and hemispheres and many cultures included it in their legends about the sky.
The ninth-brightest star night sky is Achernar. This bluish-white supergiant star lies about 139 light-years from Earth and is classified a Type B star. Its name comes from the Arabic term “ākhir an-nahr” which means “End of the River.” This is very appropriate since Achernar is part of the constellation Eridanus, the river. It’s part of the Southern Hemisphere skies, but can be seen from some parts of the Northern Hemisphere such as the southern United States and southern Europe and Asia.
Betelgeuse is the tenth-brightest star in the sky and makes the upper left shoulder of Orion, the Hunter. It’s a red supergiant classified as a type M1 and is about 13,000 times brighter than our Sun. Betelgeuse lies some 1,500 light-years away. The name comes from the Arabic term “Yad al-Jauza,” which means “arm of the mighty one”. It was translated as “Betelgeuse” by later astronomers.
To get an idea of how large this star is, if Betelgeuse were put at the center of our Sun, its outer atmosphere would extend past the orbit of Jupiter. It’s so large because it has expanded as it ages. Eventually, it will explode as a supernova sometime in the next few thousand years.
No one is quite sure exactly when that explosion will occur. Astronomers have a good idea of what will happen, however. When that star death occurs, Betelgeuse will temporarily become the brightest object in the night sky. Then, it will slowly fade out as the explosion expands. There may also be a pulsar left behind, consisting of a rapidly spinning neutron star.
Fun facts about Stars
- Most of the stars in the universe are red dwarfs.
- They twinkle because of movement in the Earth’s atmosphere.
- Many stars come in pairs called binary stars. There are some groupings with up to 4 stars.
- The smaller they are the longer they live. Giant stars are bright, but tend to burn out fast.
- The nearest star to Earth is Proxima Centauri. It is 4.2 light-years away, meaning you would have to travel at the speed of light for 4.2 years to get there.
- The Sun is around 4.5 billion years old.