Cassini

Monster Saturn Storm Created Atmospheric Hotspots | NASA JPL ESA Cassini Infrared HD Video
The LA Times had a story about a storm on Saturn that was discovered by the Cassini probe.

It was an alien storm to dim memories of all others, wrapping all the way around a vast northern portion of Saturn, a planet that could hold about 750 Earths. And it brought with it a spike in temperature never observed before anywhere in the solar system. Think of a violent storm, NASA said, that covers all of North America and continues on around the planet -- a storm from which you could not escape for nine months. - Amy Hubbard

    The video uses false colors to show what was only visible in the infrared. That's understandable, watching a gray storm on a gray planet would be pretty boring. What I found interesting was the time stamp. It is on the left center of the image and a it's a little fuzzy. It's also in a strange format. Oh, that's not a time stamp, that's a calendar stamp. This video compresses a year of watching Saturn into 15 seconds. Geez. Talk about time lapse photography.

Cassini Today

    I got to looking for more info on the probe and I found it got there in 2004 so it's been going around and around Saturn for eight years. Moreover, it took seven years to get there. That took a little planning. One of the reasons it took so long, other than Saturn is a long stinking way from us, is that it had to swing by some planets to pick up enough velocity to make it all the way out there. This voyage is, to me, the most impressive part of this project. I am sure they are doing all kinds of fascinating science there, and the orbital mechanics involved in orbiting Saturn (see picture above) are pretty impressive, but it's the getting there that impresses me.

Rough graph of Cassini's speed (red) versus time. The vertical scale is miles per second. 

The jumps are where it swings by a planet. The vertices on the blue line are the planet's velocities.
The blue line itself is there because my Graphing Fu is weak.

    We start with the launch from Earth back in 1997. As it falls toward the Sun on its way to Venus it picks up a little speed, and then when it gets there it gets a boost of a couple miles per second. Then it goes into orbit for a year, swings by Venus again (1999), gets another boost and then heads out to Earth. The difference in transit times between Earth and Venus must be due to the difference in their relative positions. The velocity difference isn't that great.
    Now we are leaving Earth for the second time, but with about five miles per second more velocity. We coast for a year and a half until we get to Jupiter where we get another little boost, and then it's a long slow slide out to Saturn, three and a half years worth.
    This whole boost thing works because

1. Planets are really big and massive and have strong gravitational fields.
2. Planets have very high velocities. They range from 3 miles per second for outliers like Neptune and Pluto to 30 miles per second for Mercury.
3. Your spacecraft is slower than the planet it is trying to get a boost from. You wouldn't do this if you were going faster, unless you wanted to slow down.
4. Your path must take you very close to the planet as it comes barreling along, kind of like a bicyclist grabbing onto the back of a truck, except it's just the gravitational pull of the planet that is acting on you.

I don't know who was driving, but they were cutting it damn close. Cassini came to 210 miles from Venus and 375 from Earth. If you knew where to look, you probably could have seen it with binoculars. It gave  Jupiter a wide berth: six million miles.

Update November 2016 replaced missing picture, replaced video with similar one from YouTube.