What is the relationship between the stars and a Nebula?

We’ve all looked up at the night sky and seen the teeny-tiny bright little dots that we know to be stars. Did you know that most stars are light-years away from Earth? Light years are a unit of measurement used by astronomers and scientists to measure the distance to which light travels in one Earth year. The speed is calculated by 300,000 kilometres per second! Yet, what do stars have to do with nebulas? Everything. Why? Because to understand where nebulas come from, we need to know how stars begin and end.

What is a star?

While stars seem like they’re incredibly small, they’re not. They are actually bigger than we think. Stars are massive, big balls of hot gas held together by gravity. They are also as bright as the sun which is why we’re able to see them twinkle in the sky all the way here on Earth. It’s just because they’re so far away that they appear to be so tiny.

The nearest star, our Sun is 8.3 light minutes, which is the length equal to the distance light travels in one minute, to Earth. Though it is physically 93 million miles away.

The next closest star is actually roughly 4.3 light years away, which is roughly 41,000,000,000,000 kilometres away! Stars come in different sizes and colours which in turn can then tell us a lot about them, for example what type of star they are. This is determined by mass and temperature.

However, stars don’t shine forever; their life span generally lasts about a million years but what happens when they die?

Death of a star

_{An image of a star in its red giant stage
Image by WikiImages from Pixabay}

The centre of the star itself contains hydrogen fuel. When that runs out, the pressure and internal temperature increase so much that it causes a nuclear reaction (yes, think mushroom clouds). The outside of the star’s shell expands and cools, turning increasingly red and then over time, grows bigger and bigger until it becomes 400 times its original size. This is when it becomes what is called a red giant. When red giants expand and grow, they engulf everything that comes close to them.

A good example or a red giant is our own Sun. It is currently expanding but the speed is so slow that it will not impact the planets in our solar system for millions of years. While Scientists are certain that the sun will engulf the planets closest to itself, they are still debating whether this will include the Earth or not.

_{A supernova
Photo credit: ernenn on Visualhunt.com / CC BY}

Another example are supernovas. A supernova is in short, a stellar explosion occurring during the last evolutionary stage of a massive star. When a supernova is at its peak optical brightness, it can be almost compared to that of an entire galaxy, before it spends several weeks or months gradually fading away.

The nebula or nebulae (singular and plural) phase

_{An image of an nebula
Photo credit: Pixabay}

A nebula is the giant cloud of dust and gas that is created from the explosion of a red giant. Amid that, the beginnings of new stars start to form. When there are more than one, they are also known as ‘star nurseries’.

The dust and gas from the explosions gravitate towards one another, fusing together and becoming larger and larger. As it grows, it also takes on its own gravitational weight before it collapses under it. The matter at the centre of the cloud heats and this is beginning of it becoming a star once again.

This is also known as stellar ignition.

The light that is produced by these new stars is enough to blow away any nearby clouds of gas but can leave enough for it to possible form new planets later on.

The nebula or nebulae is literally the gassy, cloudy space between all the stars.

The life of stars is then a never-ending circle.

How do we know this?

The earliest recorded observation of a cloud like reference in the galaxy was made by a Persian Astronomer, Abd al-Rahman al-Sufi in 964 when he was studying what we now know as the Andromeda Galaxy.

However, other astronomers throughout history have referenced them time and again. One such noted mention is from the result of a supernova in 1054.

The first detailed observations didn’t occur until the year 1659 by the famous scientist, Christiaan Huygens. Who was also the first person to define centripetal force; keeping an object moving on a curved path.

The most famous of all is Edwin Hubble. While a lot of astronomer’s and scientists flocked to the extraordinary topic, it was Hubble who lead most of the infamous strides into the nebulae themselves.

NASA even named their famous Hubble Space Telescope after him for his pioneering research and findings.

Are we able to see nebulae?

The closest nebulae to Earth are over 700 light years away and it’s called the Helix Nebula. It is possibly the remains of a star similar to our sun. An image of which can be seen below.

_{Helix Nebula
Image courtesy of pixabay.com}

Unfortunately, we are generally not able to see nebulae with our naked eye. Our capacity to see one is also dependent on how many stars are around them to illuminate through the dust clouds. It is then difficult to determine what are star clusters, galaxies or the nebulae because they’re so similar in form.

On Earth, there are many different types of observatories, where astronomer’s look at various things within our galaxy. In 1957 NASA decided to launch two Astronomical Observatories into space since our atmosphere interferes with any images taken from Earth.

In 1990 NASA also then launched The Hubble Space Telescope, which we mentioned previously and another called The Spitzer Space Telescope in 2003. By orbiting around the Earth and sending images back via radio waves, these telescopes have been able to attain images of faraway nebulae.

Scientists are still to this very day making huge discoveries in regards to our galaxies, those further away and the many clusters of nebulae in them.

Want to know more, please see the sources below.