There have been not one but TWO big solar flares recently, which have hurled huge amounts of material towards the Earth. When it arrives there's a good chance it might trigger displays of the northern lights which will be visible over Cumbria, so for the next couple of nights keep an eye on the northern sky after dark...
FIVE DAYS TO GO…
We’re now just a handful of days away from the historic landing of the Huygens spaceprobe on Titan. By Saturday, our understanding of the nature and appearance of this fascinating, mysterious moon will have been revolutionised, and every astronomy book ever written will be out of date. Professional astronomers, amateur skywatchers and space enthusiasts all over the world are breathlessly awaiting the first images from Huygens cameras, wondering if any of the space artists who have portrayed Titan’s landscape over the years got it right. Will we see lakes of methane reflecting the overcast, orange sky, as painted by space artist Ron Miller (http://planetary.org/saturn/contest/ron_miller_1024.jpg)?
Will we see bizarrely-contorted pinnacles of ice, or mounds of hydrocarbon slush? Will Huygens send back pictures of liquid ethane waves lapping in slow motion towards a distant, flat horizon? We don’t know. All we can do is wait, and guess.
( The Planetary Society recently held an art competition, giving space artists a chance to predict what Huygens cameras will show. Have a look at the winning entries here ( http://planetary.org/saturn/artcontest.html ) and see which one you think will be right!)
It’s worth taking a moment to think about the significance of this.
You may not have realised it, but this is a truly historic event. Thanks to spaceprobes such as the Pioneers, Voyagers and Vikings, we’ve all grown up knowing what the surfaces of each and every planet and its moons looks like. CCD cameras have shown us the lava-spattered surface of Io, the boulder-strewn plains of Mars and the cratered, fractured surface of Halley’s Comet. Everyone reading this email has seen pictures of heat-blasted rocks on Venus sweltering surface, the dust-filled craters of asteroid Eros and the cracked-egg face of Europa. In the past few months alone we have enjoyed spectacular views of Saturn’s two-faced moon Iapetus and many of its other satellites – but we’d already seen them thanks to Voyager and Galileo. It has been almost a generation since we saw anything really “new”, as far as planetary surfaces are concerned. Of all the major bodies in the solar system, on Friday morning only the surfaces of Pluto and Titan will be mysteries to us. By Friday night, Pluto alone will be unknown.
Think about that. We’re living in a truly golden age of exploration. And with the Pluto Express mission at least a decade away, and almost inevitably going to be delayed, we probably won’t have another such Day of Discovery until astronauts are walking on the Moon again…
That’s why Friday is so important, so historic. We’ll be seeing something – somewhere - never seen by human, or robot, eyes before.
So how did this amazing adventure start?
It all began back on the evening of March 25th 1655, forty five years after the invention of the telescope, when Dutch astronomer Christiaan Huygens turned his own instrument on Saturn – then shining modestly (just magnitude 0) in Leo, just to the left of Regulus – and saw a tiny point of light to the right of its rings. At that time the rings were almost edge on as seen from Earth, making Saturn a far less impressive sight than we’re enjoying in our own scopes right now.
Huygens named his new discovery simply Saturni Luna ("moon of Saturn"). Later, the astronomer Jean-Dominique Cassini named the four moons he discovered (Tethys, Dione, Rhea and Iapetus) Lodicea Sidera ("the stars of Louis") to honour king Louis XIV.
So how did Huygens’ discovery come to be known by its present name? Well, the name "Titan" - and the names of all seven satellites of Saturn then known - come from John Herschel, son of William Herschel, discoverer of Mimas and Enceladus. He named the moon Titan in his 1847 publication Results of Astronomical Observations made at the Cape of Good Hope.
Fitting then, that the probe which will land on Titan on Friday bears the name of the man who actually discovered the moon –the first moon to be discovered since the Galilean Satellites by Galileo himself – 350 years ago.
Christiaan Huygens was a mathematician and physicist; born in The Hague. he is commonly associated with the scientific revolution. He is generally given minor credit for his role in the development of modern calculus. A year after discovering Titan, he deducted that Saturn’s rings consisted of rocks. In the same year he observed the Orion Nebula, and using his modern telescope he was able to divide the nebula into different stars. It’s a little known fact that the brighter interior of the Orion Nebula is actually called the Huygens Region.
Another little known fact is that Huygens was one of the first writers to speculate in detail about life on other planets! In his book “Cosmotheoros” he imagined a universe brimming with life, much of it very similar to life on 17th century Earth. It was a good thing he was a native of the Netherlands, where the authorities (i.e. The Church) took quite a liberal view of such ideas. The Italian Giordano Bruno, who also believed in many extraterrestrial life, was burned at the stake for his beliefs in 1600.
Huygens moved back to The Hague in 1681 after serious illness and died there 14 years later on July 8, 1695.
And so here we are, with just 5 days to go. By Saturday morning we will have the long-awaited pictures of Titan’s surface, or at least a small part of it, which will tell us once and for all if future astronaut explorers will be faced with vast expanses of frozen, sucking organic slush, or icy plains cut by meandering rivers of exotic chemicals. On Friday night, BBC2 is showing an hour-long special all about the Huygens landing, between 11.30 and 12.30, and they should have the first pictures too. But of course, they’ll be available online first of all, and I’ll be sending out an email with a list of sites for you to Bookmark before Friday.
But even before the big day, you can join in the fun, by going outside and looking at Titan itself. You’ll need a small telescope or a powerful pair of binoculars, but it’s easy to find with quite low magnification. It looks like a star shining close to Saturn. The “Blog” has a picture showing where Titan will be on Friday night, but tonight Titan will be to Saturn’s right in your eyepiece, in the centre of a diagonal line of moons with Hyperion at the top and Iapetus at the bottom. Any planetarium program will help you identify it…
…and while you’re doing that, why not re-set your program’s date and time for March 25th 1655, so you can see Saturn – and Titan – as human eyes looked on them for the very first time, 350 years ago…
This time next week the Huygens lander should have completed its historic mission to land on Titan, Saturn’s planet-sized and most mysterious moon, and we should have the first ever pictures of its surface. What will they show?
Well, there are lots of different theories – lakes of methane, mountains of ice, etc – but we do have an idea of the kind of quality the pictures will have, and how clear they will be, because Huygen’s descent camera was tested here on Earth before the lander was sent to Titan. The probe’s instrument package was tested by dropping it over the Arizona desert… and here you can see some of the pictures it sent back during those tests!
…and if they don’t leave you drooling in anticipation of Friday’s landing, nothing will!!
When the Voyager spaceprobe visited Saturn in the early 1980s it returned pictures of the moon Iapetus which had astronomers scratching their heads in puzzlement. The moon was two-toned – one half was light, the other dark. Now the Cassini spaceprobe is orbiting Saturn and sending back far more detailed pictures than Voyager could, and the latest images of Iapetus are just stunning..!
This one shows what looks like a raised “seam” running around the icy moon. It is probably a tall, icy ridge, but no-one knows what caused it…
This one shows the cratered surface of Iapetus in greater detail than ever before…
...so does this one...
This picture shows an enormous landslide inside one of Iapetus’s huge craters..!
So what is the dark material on Iapetus? Well, some astronomers think it is material that has fallen on it from space – maybe the debris of an impacting comet? Others now think it might have welled up from inside Iapetus itself. Hopefully we’ll know soon!
This is a wonderful time to look at Saturn! It’s high in the sky late in the evening, and looks stunning in even a small telescope. The other night I had my best ever view of The Ringed Planet, and this picture shows the view through my humble 4.5 inch reflector. I could clearly see the Cassini Division – the dark gap between the major rings – and no less than five of its family of 33 moons. The brightest moon is Titan, the others are Mimas, Rhea, Dione and Tethys.
Next Friday is going to be a very important day in Saturn’s history, because that’s when the Huygens spaceprobe will be landing on its largest moon, Titan. And Titan is very easy to spot in a small telescope. Here’s a chart showing you where it will be in relation to Saturn on Friday evening.
And our view of Saturn is only going to get better over the coming month or so, as it climbs higher and higher into the sky each night. By the end of February it will be above the horizon at sunset, and visible all through the evening, so you should look at it every chance you get. This is the best view we’ll have for quite a while – soon the planet will begin to tip over and the rings will start to close-up from our point of view here on Earth, until they vanish altogether in a couple of years time. SO, make the most of them now!
We’re now just a few days away from the big day – no, not Christmas Day, I mean the day that the Huygens probe detaches itself from Cassini and starts to fall towards Titan! Actually, it does that ON Christmas Day, so we can enjoy a double celebration on that day..!
Huygens won’t actually land on Titan until January 14th, and there are lots of magazine and newspaper articles, and websites, describing in agonising detail what’s going to happen on that day, but what are the bare facts? What exactly can we expect to happen when Huygens lands on the until now hidden surface of Saturn’s largest, most mysterious moon? And what can we expect – or at least hope – to see? Well, here’s a quick CUMBRIAN SKY guide!
What is Titan?
Titan is Saturn’s largest moon. It is actually the size of a small planet – bigger than Mercury and Pluto – and is the second largest moon in the entire solar system, second only to Jupiter’s giant icy moon Ganymede.
Why is it so important?
Titan’s surface is hidden beneath a thick, smoggy, hazy atmosphere of chemicals called hydrocarbons, and some astronomers think that these chemicals “rain down” onto the surface forming deposits which might make Titan resemble the Earth’s surface how it was billions of years ago, when life was starting to develop. It’s unlikely we’ll find life itself on Titan, but the chemical “building blocks” might be there. It might also have lakes or even oceans of liquid ethane.
What is Huygens?
Huygens is a small, unmanned, European-built spaceprobe which has ridden to Saturn “piggyback” on NASA’s huge unmanned Cassini probe since its blast off in 1997. Huygens has been designed to land on Titan’s surface and send back information about its chemical composition, and photographs of its landscape too. It is packed with instruments and sensors. The probe itself looks like a big round biscuit tin, but its disc-shaped protective heat shield will make it look like a flying saucer as it plummets through Titan’s atmosphere on January 14th. Because Huygens scientists don’t know if it will land on solid ground, or splash down into a lake or ocean of liquid, it is designed to be able to float if necessary.
What is happening on December 25th?
The Huygens probe will detach from Cassini and begin a long fall down towards Titan. Landing is scheduled for Friday, January 14th 2005.
What will happen on January 14th?
On January 14th, Huygens will plummet through Titan’s thick atmosphere. After its descent is slowed by parachutes, it will land on Titan, coming down either on hard ground or in a pond, lake or ocean of liquid. It will send back information about Titan’s surface for a maximum of two hours before its batteries run out.
What will we see on the pictures taken by Huygens?
As it falls through the atmosphere, downward-pointing cameras with the same resolution as the human eye will send back detailed images of the ground below, giving us a “skydiver’s view” of Titan. As Huygens falls, its pictures will get sharper and sharper because its cameras will be looking through less and less of the moon’s thick atmosphere. From a height of 150km, Huygens’s cameras will be able to resolve surface features 200m across. When Huygens is 80km high, it will be able to see from horizon to horizon, and will start sending back dramatic panoramic views. By the time the probe is just 1km above the surface, it will be sending back pictures of surface features the size of a football!
Once on the surface, Huygens’s cameras will send back the first ever images of Titan’s surface landscape. If it lands on solid ground the pictures might show bizarre, wind-sculpted ridges and features, hills and boulders. The landscape revealed by Huygens might even be covered with strange, hydrocarbon “snow”. If the probe lands in slush, or mud, we might see splashes of material spreading away from it. If it lands in liquid, we may see a perfectly flat horizon, or tall waves, with Titan’s orange sky above. The view might tilt this way and that on different images as the probe rolls in the waves.
Although many works of “space art” show it, one thing we won’t see in any of Huygens’s surface pictures is Saturn. The moon’s atmosphere is far too thick. So when human explorers visit Titan in the far future, unfortunately they won't enjoy a view like this...
So, that’s what we’ll see. All we can do now is cross our fingers – and wait!
Here are some new finder charts for Comet Machholz, which is apparently brightening nicely, and should be visible to the naked eye when the Moon gets out of the way...!
January 7th (near the famous Pleiades star cluster)
Here you'll find some pictures of Comet Machholz, too...
Remember, all you need to see this comet is a simple pair of binoculars, you don't need a telescope!
The CASSINI spaceprobe has made its last pass of Titan before the historic January 14th landing of the Huygens lander on the giant moon’s surface. Although the pictures returned during this latest fly-by are nowhere near as clear as the images taken of the other moons orbiting Saturn, they do show some tantalising details on Titan’s surface and in its atmosphere…
Click here for an image of Titan’s disc, seen during the close encounter.
Click here and here for close-ups of Titan’s atmosphere.
Click here and here for stunning images showing Titan lit from behind..!
On October 26th the CASSINI spaceprobe made its first fly-by of Saturn’s giant moon Titan, and sent back the first ever detailed pictures of its surface. On Monday December 13th, the probe will make its second fly-past, and the pictures it sends back should be even better!
We’re already getting some images from the probe, and you can see one of them here…
And if you want to keep track of the fly-past, and see the new pictures as soon as they’re released, you should go to these websites and bookmark them right now, so you can check the pictures on Monday evening...