July 19th was ‘Wave at Saturn’ day, the day Cassini took our picture from in orbit around Saturn (so I do hope you waved). I feel, therefore, it’s time to post the promised and hotly anticipated Part II of my favourite pictures from the mission so far. Part I can be found here.
A few days ago I read an article about plans for NASA’s & ASI’s Cassini probe to take a picture of the Earth from its orbit around Saturn, in the same vein as Carl Sagan’s Pale Blue Dot taken by the Voyager 1 probe. This type of picture really drives home how insignificantly small and delicate the Earth is as it floats through the Universe, and I’m sure the new picture will instil people with the same sense of wonder and/or horror that its predecessor did. The Cassini-Huygens mission has expanded our knowledge of the Solar System so much during its time that I’ve wanted to write about it for a while. And by “write about it” I obviously mean “post nice pictures”.
So here is Part I of my favourite images taken by Cassini, and its companion on the long journey to Saturn, ESA’s Huygens probe. All are click-able if you want to open them up for full-screen viewing.
It’s now almost a century since Albert Einstein published his general theory of relativity and we’re still trying to find a flaw in it. It remains our best theory of space, time and gravity. But, as ever in science, we’re constantly striving to test it in new ways in the hope that some experiment or observation will disagree with the theoretical prediction. We hope this because it’s certain that general relativity isn’t the full picture.
Recent discoveries just might help reveal what we’re missing.
2013 looks set to be an interesting year for those of us residing in the Milky Way (page view stats indicate this applies to the majority of visitors to this blog). In the middle of this year, the supermassive black hole in the centre of our galaxy will be paid a visit by a cloud of gas with a mass three times that of the Earth. This could result in a bright flare of X-rays if some of this gas falls too near the black hole and is consumed, allowing us to probe the environment around it better than ever before. But how do we know there’s a black hole there in the first place, and why won’t this gas just get gobbled up without a trace?
Recently I was talking to somebody about the expansion of the Universe and they asked me a very good question,
“If space goes on forever, how can it be expanding?”
This is related to one I’ve been asked quite often,
“What’s the Universe expanding into?”
It seems obvious at first thought that if something is expanding it must be doing so into some sort of surrounding space, some ‘outside’. So something without an edge, like infinite space, has no ‘outside’ to expand into and therefore can’t expand. The problem here is that our personal experiences in the world tell us one thing, but physics and maths tell us another, and to relate these is very tricky.