Nebulae are clouds formed by cosmic dust, plasma, hydrogen and ionized gases, usually released from the death of a star.
They are also known as "cradle of stars", as the gravitational attraction within them can cause matter to clump together and form a new star.
This means that nebulae can be the starting point and the ending point of the evolution of stars.
Nebulae have undefined shapes and variable sizes. They can be the size of a star like the Sun or reach the size of a galaxy and are measured in light years.
The word nebula is derived from the Latin term "nebula", which means cloud. This name was given by astronomers due to the similarity to a cloud.
Lagoa Nebula or NGC 6523.
Types of Nebulae
diffuse nebulae
They are nebulae whose boundaries are not well defined. They are classified into emission and reflection nebulae, according to their behavior with visible light.
emission nebula
Emission nebulae are clouds of high-temperature gases with a high concentration of ionized hydrogen, the most common gas in the universe. Due to the large amount of hydrogen, these nebulae usually emit reddish colors.
These nebulae absorb the light emitted by ultraviolet rays from nearby stars and when they drop to a lower energy state they release visible light. Some examples of emission nebulae are the Eagle Nebula and the Omega Nebula.
Learn more about hydrogen.
reflection nebulae
Reflection nebulae are clouds of gas and dust that only reflect light from nearby stars. Due to the greater ease of dispersion of the blue color, these nebulae are usually seen in bluish tones.
Reflection nebulae are often sites of star formation and are often seen together with emission nebulae. One of the most famous reflection nebulae is the Orion Nebula, located in the belt of Orion.
dark nebulae
Dark nebulae are very dense, cold clouds of dust and gas that do not allow light to pass through, nor do they emit visible light. They are visualized as a darker patch surrounded by brighter, starry parts of the sky.
The most famous dark nebulae are: the Bag of Coal Nebula, which can be seen with the naked eye from Earth, and the Nebula Horsehead, which was first observed in 1888, from an observatory at the University of Harvard.
planetary nebulae
Planetary nebulae are so named because the first astronomer to observe them, William Herschel, believed they were gaseous planets. These nebulae form in the final stage of life or at the death of a small-mass star.
Some examples of planetary nebulae are the Helix Nebula and the Butterfly Nebula. No planetary nebula can be seen with the naked eye.
examples of nebulae
Helix Nebula
Located in the constellation Aquarius, 700 light-years away, this is one of the closest nebulae to planet Earth. Due to its shape, the Helix Nebula is popularly known as "eye of god".
This nebula was formed from the death of a star, so it is classified as a planetary nebula.
Helix Nebula or NGC 7293.
Understand how the unit of measure works light-years.
butterfly nebula
With an incredible shape of the wings of a butterfly, this nebula is one of the most beautiful that is known. It is located in the constellation Scorpio, 4,000 light years from Earth.
Formed from the death of a small star, it is a planetary nebula.
Butterfly Nebula or NGC 6302.
Orion Nebula
Orion is one of the most famous nebulae and can be seen with the naked eye on Earth. Its name comes from its location: it is positioned in the Belt of Orion, at 1270 light years and is 3 light years across.
Within the Orion nebula there are about 700 stars in different stages of life.
Orion Nebula or NGC 1976.
Horse Head Nebula
This nebula is named for its shape, which resembles the animal's head. It is dark in color as it is composed of a dense mass of cosmic dust.
The Horsehead Nebula is located 1500 light years from Earth and is a dark nebula.
Horsehead Nebula or Barnard 33.
Understand more about the stars.
