Saturn’s moon may have rings – the first ever discovered

Everyone knows that Saturn has rings, but what about its moons? Surely they don’t have rings as well? Well actually, Rhea, a moon of Saturn that is usually overlooked, may be the first moon ever discovered to have rings, thanks to new research from the NASA/ESA Cassini-Huygens mission.

Rhea’s rings aren’t particularly impressive compared to Saturn’s – after all, it’s hard to imagine anything having a more impressive ring system that the huge gas giant Saturn. In fact, they haven’t even been photographed yet, but there is strong evidence to show that they exist.

How did the scientists work out that Rhea had rings without even seeing them? It’s all down to electrons, tiny charged particles that surround Saturn in its magnetic field. Because Rhea lies within the magnetic field of Saturn, it was expected to be seen ‘clearing up’ some of the electrons, because Rhea would absorb electrons from the magnetic field.

Rhea certainly did clear up the electrons – but it did it far better than expected, absorbing electrons about 7 times further away than it should have done. Why? The only feasible answer seems to be that Rhea has a ring system, and that the ring particles are absorbing the extra electrons.

Rhea is just one of a group of Saturn’s 52+ moons that are intriguing scientists: Rhea’s cousin Titan has methane lakes and rain; Iapetus is half-black and half-white; Enceladus has an atmosphere. The Cassini-Huygens mission is making it obvious that Saturn’s moons are just as interesting as the ringed planet itself.

NASA’s plan to put a telescope on the Moon

Over the last 50 years we’ve managed to get telescopes pretty much everywhere: from the remote Atacama desert to the peaks of Hawaiian volcanoes and even to outer space, we’ve got giant eyes on the Universe set up all over the place. But what about a telescope on the Moon?

Well, that may be happening soon as well. NASA has announced that it’s funding a year-long research project into the feasibility of having a telescope on the Moon – although it will not even start being constructed until 2025, so don’t get too excited yet.

The obvious thing to ask is what is the point in spending $1 billion putting a telescope on the Moon?

It’s all down to the problem of interference on Earth. The type of waves that the Moon telescope would be detecting are radio waves, which are distorted by Earth’s atmosphere so much that they become almost useless. Add to that the huge amount of radio waves being produced for our TVs – and of course radios – and it just becomes impossible to do anything with radio waves on Earth.

A telescope on the dark side of the Moon would be permanently out of the reach of all this disturbance, giving crystal clear views of our Universe.

Why radio waves? We already know quite a bit about the extremely early Universe because of the Cosmic Microwave Background. And we also know a lot about the Universe since the time of the first galaxies, because we can use telescopes to see our Universe in evolution over those billions of years. Radio wave telescopes are necessary to see the time in between – when the Universe was starting to become more stable, but hadn’t yet started producing galaxies.

Discovering more about this era in our Universe’s history could unleash a revolution in our knowledge of dark matter – one of the last things about the Universe that we know virtually nothing about. Will NASA approve the telescope? I certainly hope so – and I’m quite confident that they will.

NPR’s Science Friday did a fascinating interview with the woman leading this research project – click here to listen.

The oldest galaxy ever seen: Looking back in time with Hubble

It’s a well-known fact among astronomers that if you look at the Sun, you are looking back in time – fast as light is, it still takes 8 minutes to travel those 93 million miles. Likewise, when you look at the Moon, you are actually seeing it as it was 1.3 seconds ago, not as it is right now. So imagine looking at something so far away that its light took 13 billion years to reach us – that would mean we would be looking back in time 13 billion years, back to just after the dawn of time.

Well, NASA scientists using the Hubble and Spitzer Space telescopes have done just that, imaging one of the first ever galaxies to exist (see image below). Without vital pioneer galaxies like this one, our own Milky Way galaxy would not exist today.

So how is it possible to see so far back in time? It’s all down to a clever trick known as gravitational lensing. Basically, when you have a big object such as a galaxy, Einstein’s theory of relativity says that it will bend everything toward it sightly – light included.

The light from the 13 billion year old galaxy (A1689-zD1) was bent toward a second galaxy that is much closer to us, and this not only distorted the original galaxy’s light, but also made it appear much bigger.

In this image it is only possible to see the main bands of stars in the ancient galaxy. But get this: by 2013, when the James Webb Space Telescope (Hubble’s mega-successor) is launched, we will be able to resolve individual stars in this galaxy, even though it is so far away. And we will be able to see even further back in time, to galaxies even older than this one.

Hyakutake1957 has written a fascinating post with even more detail over on his blog.