The Eye of God

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There was an email going around a few years ago talking about “the Eye of God”. This photo was actually an image of the Helix Nebula taken by the Hubble Space Telescope.

The Eye of God nebula is a bright planetary nebula located about 700 light-years away in the constellation Aquarius; it’s also known as NGC 7293. In fact, the Helix Nebula is probably the closest planetary nebula we can see in the sky, and it shows the future that stars like our Sun go through when they run out of fuel and puff out their outer layers.

It’s thought that the Helix Nebula is actually cylindrical shaped. From our perspective, we’re looking down the cylinder to see the central star. Astronomers estimate that the Helix Nebula is about 10,600 years old, based on the rate of expansion of the nebula.

With the power of the Hubble Space Telescope, astronomers were able to see knots of material in the nebula. They’ve now discovered more than 20,000 of these cometary knots in the nebula. These knots have cometary tails, and it’s been discovered that they can collide with one another.

Here’s the email you might get:

Subject: Fw: Eye of God
This is a picture taken by NASA with the Hubble telescope. They are referring to it as the “Eye of God”. I thought it was beautiful and worth sharing.

Some emails even say that this is a rare event that only happens once every 3,000 years. The reality is that this is just a beautiful photograph taken by the Hubble Space Telescope. There are other images that have been taken by other telescopes and they look beautiful as well.

We’ve written several articles about the Helix Nebula for Universe Today. Here’s an article about a new view into the Helix Nebula, and here’s an article about comets colliding inside the Helix Nebula.

If you’d like more info on the Helix Nebula, here’s a nice picture from the La Silla Observatory at Astronomy Picture of the Day.

We’ve also recorded an entire episode of Astronomy Cast just about nebulae. Listen here, Episode 111: Nebulae.

Helix Nebula

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The Helix Nebula is one of the most familiar nebulae in astronomy, and it’s been nicknamed the “Eye of God”. Its official designation is NGC 7293, the Helix Nebula is located inside the constellation of Aquarius. The Helix Nebula is one of the closest examples of a planetary nebula. Astronomers have estimated its distance to only be 700 light-years away.

The central star of the Helix Nebula was once a star very similar to our own Sun. As the star neared the end of its life, it expanded into a red giant and puffed away its outer layers. The central star is destined to become a white dwarf star, as it slowly cools down. It’s no longer actively fusing hydrogen, and only shines with the remaining heat from when it was once a star.

The Helix Nebula that we see today is actually just a momentary phase in the death of the star. The inner layers of gas and dust expanding away from the central star were probably released about 6,500 years ago, with the outer layer released about 12,000 years ago. We can see them because they’re illuminated by the central star. But eventually they’ll get far enough away that they’re no longer bright enough to see. From that point on we’ll just see the central white dwarf star.

Because the Helix Nebula is so close, images from the Hubble Space Telescope revealed knots of material in the expanding shells of gas and dust. There are more than 20,000 of these knots in the nebula, and they have cometlike tails stretching away from the central star.

We’ve written many articles about the Eye of God nebula for Universe Today. Here’s an article about a new view into the Helix Nebula, and here’s an article about comets colliding inside the Helix Nebula.

Here’s a nice photograph of the Helix Nebula taken by the Hubble Space Telescope.

We’ve also recorded an episode of Astronomy Cast all about nebulae. Listen here, Episode 111: Nebulae.

Nebula Pictures

Here are some cool nebula pictures taken by the Hubble Space Telescope.

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This is a cool picture of the Omega Nebula, which is also known as the Swan Nebula, or M 17. It’s located in the constellation Sagittarius, located about 5,000 light-years from Earth.


Cat's Eye Nebula
Cat's Eye Nebula

This is picture of the Cat’s Eye Nebula, a planetary nebula in the constellation Draco. This used to be a star similar to our Sun, but then it died and became a white dwarf, puffing off its outer layers into space.


Carina Nebula
Carina Nebula

This is the Carina Nebula, a star forming nebula in the Carina Constellation. It holds Eta Carinae, one of the most massive stars ever discovered, which is expected to detonate as a supernova in the next few hundred thousand years.


Bubble Nebula. Image credit: Hubble
Bubble Nebula. Image credit: Hubble

This is the Bubble Nebula, also known as NGC 7635. This nebula glows because of a hot central star that’s providing radiation and exciting the nebula atoms.


Full view of the Trifid Nebula.  Credit: ESO
Full view of the Trifid Nebula. Credit: ESO

This is a picture of the Trifid Nebula taken by the European Southern Observatory. This nebula was cataloged M 20 by Charles Messier as part of his famous catalog. It’s called the “Trifid Nebula”, because it appears to be broken up into three parts.

We have written many stories about nebulae for Universe Today. Here’s an article with more details about the Trifid Nebula, and here’s an article about planetary nebulae found around heavy stars.

If you want more cool pictures of nebula, you should check out the source. Go to the Hubble Space Telescope page on nebulae.

We have recorded an entire episode of Astronomy Cast that’s just about nebulae. Listen here, Episode 111: Nebulae.

What Is The Crab Nebula?

The Crab Nebula, or M1 (the first object in Messier’s famous catalog), is a supernova remnant and pulsar wind nebula. The name – Crab Nebula – is due to the Earl of Rosse, who thought it looked like a crab; it’s not in the constellation Cancer (the Crab), rather Taurus (the Bull).

The supernova which gave rise to the Crab Nebula was seen widely here on Earth in 1054 (and so it’s called SN 1054 by astronomers); it is perhaps the most famous of the historical supernovae. It is certainly one of the brightest (estimated to be –7 at peak), partly because it is so close (only 6,300 light-years away), and partly because it’s not hidden by dust clouds. The expansion of the nebula – as in seen-to-be-getting-bigger, rather than the-gas-is-moving-very-fast – was first confirmed in 1930.

As it was a core collapse supernova (a massive star which ran out of fuel), it left behind a neutron star; by chance, we are in line with its ‘lighthouse beam’, so we see it as a pulsar (all young neutron stars are pulsars, but not all of them have beams which point to us in one part of the cycle). It’s a pretty fast pulsar; the neutron star rotates once every 33 milliseconds. Because it’s so young and so close, the Crab Nebula pulsar was the first to be detected in the visual waveband, and also in x-rays and gamma rays. Being the source of the tremendous output of energy, from both the pulsar wind nebula and the pulsar itself, and as energy is conserved, the pulsar is slowing down, at a rate of 15 microseconds per year.

The inner part of the Crab Nebula, the pulsar wind nebula, contains lots of really hot (‘relativistic’) electrons spiraling around magnetic fields; this creates the eerie blue glow … synchrotron radiation. This makes the Crab Nebula one of the brightest objects in the x-ray and gamma ray region of the electromagnetic spectrum, and as it is a relatively steady source (unlike most high energy objects) it has given its name to a new astronomical unit, the Crab. For example, a new x-ray source may be 2 mCrab (milli-Crab), meaning 0.002 times as strong an x-ray source as the Crab Nebula.

This SEDS page has a lot more information on the Crab Nebula, both historical and contemporary.

Such an intensively studied object, no wonder there are lots of Universe Today stories on it; for example Nearly a Thousand Years After the Death of a Star, Giant Hubble Mosaic of the Crab Nebula, The Peculiar Pulsar in the Crab Nebula, Astronomers Locate High Energy Emissions from the Crab Nebula, and Evidence of Supernovae Found in Ice Core Sample.

Astronomy Cast’s Neutron Stars and Their Exotic Cousins has more on pulsars, and Nebulae more on nebulae.

Sources: Caltech Astronomy, SEDS, Stanford University SLAC