“Fly me to the moon

Let me play among the stars

Let me see what spring is like

On a-Jupiter and Mars”

– Frank Sinatra, “Fly Me to the Moon”

This week I had the honour of meeting three legends of the 20th century; astronauts Capt. Neil Armstrong, Capt. Gene Cernan and Capt. Jim Lovell. Neil Armstrong is, of course, the first man to set foot on the moon (Apollo 11), Jim Lovell was the commander of Apollo 13 and Gene Cernan was the last man to walk on the moon (Apollo 17).

Right to left: Capt. Gene Cernan, Capt. Neil Armstrong and Capt. Jim Lovell

The astronauts were talking on behalf of the Foundation for Science and Technology at the Royal Society and Cernan and Lovell both spoke of their disappointment at the US plans to abandon the “Constellation” programme which aimed to put astronauts back on the moon by 2020. Cernan said that, walking on the moon in 1972, he never would have imagined that he would still be the last man to set foot on the moon’s suface over 37 years later. The astronauts also talked of their hope that they would be alive to see man set foot on Mars.

Politics aside, it was fascinating to hear the astronauts speak about their experiences. All of the astronauts agreed that travelling to the moon changed their perspective of life on Earth. Cernan said it was staring out of the window into the black “infinity of space”, whereas Lovell said it was looking back from the moon and “being able to cover the entire World with my thumb” that was the most life changing moment.

My Ring of the Week this week is Galaxy Zoo image 587741708326863123 and is in honour of Neil Armstrong and his lunar module, the Eagle. You can see the ring on the bottom right of the image and an unusual, bird-shaped “Eagle” galaxy on the top left. The “Eagle” galaxy is at the same redshift as the ring and so at the same distance away from us. This means that the two galaxies are most likely interacting in some way.

It could be that the “Eagle” is a polar ring (see last week’s post), where stars have been gravitationally stripped from the larger ring galaxy to rotate around the poles of the smaller galaxy. Or perhaps this is a collisional ring system, the “Eagle” having crashed through the centre of the larger galaxy to create the blue ring of stars that we see on the bottom right of the image. At the moment I’m not quite sure exactly which option (if either!) is the right one so feel free to post your own ideas about what you think may be happening and I’ll let you know if I figure it out!

“Up on a hill, as the day dissolves
With my pencil turning moments into line
High above in the violet sky
A silent silver plane – it draws a golden chain

One by one, all the stars appear
As the great winds of the planet spiral in
Spinning away, like the night sky at Arles
In the million insect storm, the constellations form

On a hill, under a raven sky
I have no idea exactly what I’ve drawn
Some kind of change, some kind of spinning away
With every single line moving further out in time”
– Brian Eno, “Spinning Away”

Well if you ask me, what you’ve drawn there Brian is a “Polar Ring” galaxy.

Polar ring galaxies, unlike all other galaxies in the Universe, are made up of two distinct parts. In the centre we have a normal galaxy and around the outside we have a “golden chain” of stars and gas clouds. This ring is perpendicular to the “silver plane” of the host galaxy disk, rotating over the poles, and so it’s known as a polar ring.

So how are polar rings formed? Polar rings are thought to form when two galaxies gravitationally interact with each other. We believe that “one by one, all the stars appear” as they are stripped from a passing galaxy and “spiral in” to produce the polar ring we see today. Polar rings, although not quite as rare as smoke rings, are pretty hard to find. According to “New observations and a photographic atlas of polar-ring galaxies”, about 1 in every 200 lenticular galaxies (a type of galaxy between an elliptical and a spiral) have these “golden chains” of stars and gas spinning around them. Below is a selection of some of my favourite polar rings from the Galaxy Zoo:

The Zooites have done fantastically well at finding Polar Rings and you can see all of their incredible finds on the Possible Polar Ring thread on the Galaxy Zoo forum.

My Ring of the Week this week is the stunning pair of interacting galaxies Arp 87. Located in the constellation Leo, approximately 300 million light years away from Earth, Arp 87 gives us a fantastic insight in to exactly how polar ring galaxies are formed. The image on the left is the Galaxy Zoo Arp 87 image and on the right is an image taken by the Hubble Space Telescope. We can clearly see the galaxy on the left gravitationally stripping away the stars and gas from the spiral galaxy on the right.

Unfortunately for Brian Eno, his hypothesis of a “golden chain” of stars that “spiral in” a “silver plane” came a full 23 years after the first polar ring galaxy was identified by J. L. Sérsic in 1967.

However, perhaps someone else had already had a genuine polar ring premonition a full 78 years before Sérsic’s discovery…?

– “Starry Night” 1889, Vincent Van Gogh

The Hubble image is part of a collection of 59 images of merging galaxies released on the occasion of its 18th anniversary on April 24, 2008. (NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University))