Happy Tenth, Cassini!

Cassini has been at Saturn for ten years now. Ten years! From among my favorites:




As always, see the Cassini home page for more.

Happy Tenth, Cassini!

Cassini has been at Saturn for ten years now. Ten years! From among my favorites:


Wow... sunlight filtering through and reflecting off the rings to illuminate Saturn's southern hemisphere while the north remains in darkness. Note how dark the B-ring looks, its density blocking the sun's light. Below lurks Tethys, barely visible.

We keep seeing wondrous things through Cassini's eyes. Prometheus (102 kilometers, or 63 miles across) is seen here with two long streamers of material that it has pulled out of the F ring. When Prometheus comes close to the F ring in its orbit, the moon's gravity tugs on the ring particles. The disturbed particles, now pulled into orbits slightly closer to Saturn and therefore faster, shear out during successive orbits, creating the long and delicate streamers seen here.


Three of Saturn's smaller moons and its rings - from Mimas (at the top outside the rings altogether, 397 kilometers, or 247 miles across) to Pandora ( outside the F ring and 84 kilometers, or 52 miles across) to little Atlas (to the left, between the F and A rings and only 32 kilometers, or 20 miles across). This picture was taken from below the rings by Cassini in September 2007; doesn't it appear as if we're looking down, though? But we're looking up, so Pandora is closest to us, not farthest!


As always, see the Cassini home page for more.

Happy Tenth, Cassini!

Cassini has been at Saturn for ten years now. Ten years! From among my favorites:

There are four moons here:



The most obvious one is Dione, of course, bright and in the center of the shot. Behind Dione is giant Titan. Off to the right, at the tip of the rings, is little Pandora, an F-ring shepherd. Did you find the fourth one?

Look at the rings. See the dark gap? That's the Encke gap. Look closely. See the bright speck? That's Pan - tiny, tiny Pan, only 35 km (21.7 miles) across. Pan is a ring shepherd, and helps maintain the Encke Gap, keeping it clear of ring particles.

Here's a truly stunning image from Cassini, Rhea and the rings. It's raw, unprocessed - and amazing.



What moon is that? How can a moon of Saturn be so centered on the A Ring?

Well, it can't. That's no moon, folks, that's a star! And it's behind the rings.

It's Mimosa, aka Beta Crucis, the bright left-hand star in the Southern Cross. The rings, being particles, let light through, and this star's so bright it looks as though it's in front.


Cassini took this picture in infrared (which is why it's dark) just as Rhea moved behind Saturn. Further out along the rings are Tethys and Enceladus at far left.

As always, see the Cassini home page for more.

Happy Tenth, Cassini!

Cassini has been at Saturn for ten years now. Ten years! From among my favorites:



Oh. My.


Cassini was above the ringplane when it took this picture - a slice of the entire ring system.

The rings are lit by sunlight from below; the light scatters through the rings' particles, but much of it bounces off their undersides and illumines Saturn's southern hemisphere. It also casts a shadow of the inner rings across the northern hemisphere - and Saturn's own shadow slices across the rings on the left side of the photo.

Oh. Wow.

Check this out. Looking down from above - Saturn and its shadow, the entire set of rings, one moon (Janus - center, outside the rings), and two stars (lower down, flanking the outer F ring) ... There are some "spokes" - cloudy irregularities - in the B ring, the darker section of rings in the center.

As always, see the Cassini home page for more.

Happy Tenth, Cassini!

Cassini has been at Saturn for ten years now. Ten years! From among my favorites:


This moody true color portrait of Saturn shows a world that can, at times, seem as serene and peaceful as it is frigid and hostile. Saturn's unlit-side rings embrace the planet while their shadows caress the northern hemisphere.
Janus (181 kilometers, or 113 miles across) is a mere speck below the rings, just left of the terminator. The view was obtained from about 15 degrees above the ringplane as Cassini continued its climb to higher orbital inclinations.

Dione and Atlas and the rings... Atlas? Yes - select the picture and look just below and to the left of Dione and behind the rings.

From 24 degrees above the unlit rings, Cassini gazes down at the A Ring, with tiny Pan in the Encke Gap and the F Ring at the far outside (the bottom of the shot). Saturn is visible through the ring.

As always, see the Cassini home page for more.

Whaaaaaa?

Seriously, people? 1998? Last American to stay there? The International Space Station? There are three Americans there right now.

How did 2 of 3 contestants not know that? (The answer was Mir.)

ps - Pat Sajak just said, apropos of a puzzle "Star on the Hollywood Walk of Fame": "I have a star on the walk of fame. Vanna has a star. Alex Trebek has a pentagram - it's very odd."

Happy Birthday, Nicolaus

Born today in 1473, the originator of the theory which bears his name - the Copernican, or heliocentric, system, which challenged and then (for most people) replaced the geocentric system, which held that the earth was the center and everything revolves around it. Nicolaus Copernicus was a brilliant polymath who merely dabbled in astronomy, and yet he removed the geocentered (and anthrocentered) universe from the realm of science.

He died in 1543, apparently, of a stroke, and legend has it that he regained consciousness in time for the first printed copy of his, if you'll pardon the pun, revolutionary work De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres) to be placed into his hands, allowing him to see his life's work before he died. It's only a legend, but it's a nice one, isn't it?

(painting by Jan Matejko, displayed in the Nicholaus Copernicus Museum in Frombork)

And let's not forget to teach the controversy! Ha

Also - nice Google Doodle for today!

Happy Birthday, Johannes

Today in 1571 Johannes Kepler was born in Wurttemberg, Germany. Kepler was born to Lutheran parents, but never subscribed fully to the doctrine of "the real presence" and refused to sign the Formula of Concord; therefor he was excluded from the sacrament. Being unaccepted by the Lutherans and not a Catholic, either, Kepler had no refuge during the Thirty Years War and the counter-reformation, which meant he was forced to move over and over again to stay alive.

I quote from the biography of Kepler on NASA's Kepler Mission page, where you can go for more details on his work and his three laws (my emphasis):

Kepler was forced to leave his teaching post at Graz due to the counter Reformation because he was Lutheran and moved to Prague to work with the renowned Danish astronomer, Tycho Brahe. He inherited Tycho's post as Imperial Mathematician when Tycho died in 1601. Using the precise data that Tycho had collected, Kepler discovered that the orbit of Mars was an ellipse. In 1609 he published Astronomia Nova, delineating his discoveries, which are now called Kepler's first two laws of planetary motion. And what is just as important about this work, "it is the first published account wherein a scientist documents how he has coped with the multitude of imperfect data to forge a theory of surpassing accuracy" (O. Gingerich in forward to Johannes Kepler New Astronomy translated by W. Donahue, Cambridge Univ Press, 1992), a fundamental law of nature. Today we call this the scientific method.

In 1612 Lutherans were forced out of Prague, so Kepler moved on to Linz. His wife and two sons had recently died. He remarried happily, but had many personal and financial troubles. Two infant daughters died and Kepler had to return to Württemburg where he successfully defended his mother against charges of witchcraft. In 1619 he published Harmonices Mundi, in which he describes his "third law."

In spite of more forced relocations, Kepler published the seven-volume Epitome Astronomiae in 1621. This was his most influential work and discussed all of heliocentric astronomy in a systematic way. He then went on to complete the Rudolphine Tables that Tycho had started long ago. These included calculations using logarithms, which he developed, and provided perpetual tables for calculating planetary positions for any past or future date. Kepler used the tables to predict a pair of transits by Mercury and Venus of the Sun, although he did not live to witness the events.

Johannes Kepler died in Regensburg in 1630, while on a journey from his home in Sagan to collect a debt. His grave was demolished within two years because of the Thirty Years War. Frail of body, but robust in mind and spirit, Kepler was scrupulously honest to the data.

What a tremendous epitaph that is.

ISS ... still up there

The ISS is still up there, and even has two Americans on board, along with a Canadian and three Russians.

It's very odd to me why we don't hear more about that. I know manned space flight is a waste of resources to a lot of people, and that the robots (Discovery, Curiosity, Spirit) are doing exciting work a lot further away, but ...

We have a space station! Not a big one, but it's there. That's really exciting.

Happy Birthday, Frederick

Frederick William Herschel, born Friedrich Wilhelm Herschel, was born today in 1738. Herschel is most famous for the discovery of Uranus in addition to two of its major moons, Titania and Oberon. He also discovered two moons of Saturn - Enceladus and Mimas, shown below (they're tiny! yet large enough to be rounded by self-gravity), Enceladus against the clouds and Mimas below the rings. Mimas, by the way, is the "Death Star moon", its huge Herschel crater prominent in the photo at the bottom.

Curiosity!

(imgage source)

Mars is so far away that all of the landing sequences had to be automated, with no way to correct them. But Curiosity landed perfectly - and NASA even got a picture of it as it happened, with another satellite pre-positioned to get the shot.

Curiosity's YouTube Channel

Sometimes I'm just so proud of us.

Happy Birthday to quite a few

A number of people were born today, including Emmanuel Ax, in 1949 - I love his playing; Francis Crick, in 1916, who helped discover DNA; John W Campbell, in 1910, arguably the greatest influence on science fiction ever; and Giovanni Domenico Cassini, in 1625, who discovered the Cassini Gap in the rings of Saturn, the broad black band in the 2004 Hubble telescope's picture below...

Happy Birthday, William

William Wallace Campbell was born today on a farm in Ohio, in 1862. He was a a pioneer of astronomical spectroscopy and catalogued the radial velocities of stars, was director of the Lick Observatory for 30 years, and led expeditions to photograph stars and solar eclipses in the Southern Hemisphere, one of which provided further evidence supporting Albert Einstein's theory of relativity. His obituary in the Monthly Notices of the Royal Astronomical Society, Vol. 99, p.317, says, in small part:

Campbell was not one of those blown about by every idle wind of astronomical doctrine; no-one ever called him a weather-vane. And the implication that he was not especially receptive to new tenors of thought is true. His method was to push ahead in his own established line of research rather than to experiment with trial balloons in the hope of reaching other levels. He has been criticized on this score, but, if criticism be limited to those who have accomplished as much as he, not many are entitled to be heard.

"We Stopped Dreaming"

I remember years ago when Apollo 13 had just come out on video, I was in Saturday Matinee and they were playing it on the store's TV monitors. They had gotten to the point in the movie where the Saturn is lifting off the launching pad. I was just standing there watching, and a man about my age was standing next to me, mesmerized.

"Do you remember that?" he asked me.

"I do," I said. "We saw a couple."

"God, I wish I had," he said. His young son was with him. After a while he came up and stared at the screen, but after a moment he looked at his father and said, "Dad, what's that?"

"That," his father said, "is a spaceship."

His son looked at the screen, with a skeptical expression. "A spaceship? Really?"

"Yes. Really." He paused. "It was a real spaceship." His voice almost broke as he added, "And it was ours."

Happy Birthday, Percival

Today in 1855, Percival Lowell was born. He didn't discover Pluto, but his belief that Planet X lay beyond Neptune and Uranus and perturbed their orbits led to its discovery. Pluto of course isn't big enough to be "Planet X" - in fact, the whole "Planet X" thing was due to a mistake in measuring the mass of Neptune.

When you couple that with Pluto's subsequent reclassification; Lowell's mass building of observatories and funding programs; his enormous popularization efforts; and his obsessive drawings of canals and oases on Mars, the remnants of a desperate and dying ancient civilization ... well, you do have to admit that maybe Lowell had more money than sense.

Still, he contributed an enormous amount to astronomy and science fiction, and so we should be grateful. Let's raise a glass and pull out our Wells or our Bradbury or even our Burroughs and wish Percival Lowell a happy birthday!

Happy Birthday, William

Frederick William Herschel, born Friedrich Wilhelm Herschel, was born today in 1738. Herschel is most famous for the discovery of Uranus in addition to two of its major moons, Titania and Oberon. He also discovered two moons of Saturn - Enceladus and Mimas, shown below (they're tiny! yet large enough to be rounded by self-gravity), Enceladus against the clouds and Mimas below the rings. Mimas, by the way, is the "Death Star moon", its huge Herschel crater prominent in the photo at the bottom.

A shadow in the sky

Wow. Just ... wow.



Mt Ranier definitely dominates the landscape when it's out. But in the fall and early winter, as the sun moves towards the south, Ranier can also dominate the dawn sky - especially with clouds to help. At more than 14,000 feet, when the top of the mountain blocks the sun's first rays, the shadow goes on ... forever, it looks like. Just wow. This particular shot was taken by Nick Lippert in Tumwater, Washington. There are more at the link below.

(source and more photos KOMO News.com)

Four Moons

It's been quite a while, hasn't it? But here's another gorgeous photo from Cassini: four moons and the edge of the rings. Ids are below the photo - see if you can spot all four. (Select the photo for a bigger version; you might need it!)



The most obvious one is Dione, of course, bright and in the center of the shot. Behind Dione is giant Titan. Off to the right, at the tip of the rings, is little Pandora, an F-ring shepherd. Did you find the fourth one?

Look at the rings. See the dark gap? That's the Encke gap. Look closely. See the bright speck? That's Pan - tiny, tiny Pan, only 35 km (21.7 miles) across. Pan is a ring shepherd, and helps maintain the Encke Gap, keeping it clear of ring particles.

As always, see the Cassini home page for more.

Highest mountain in solar system

Ummmmm.

Jupiter is a gas giant. It doesn't have any mountains on it!

Mons Olympus is on Mars.

Happy Birthday, all!

A number of people were born today, including Emmanuel Ax, in 1949 - I love his playing; Francis Crick, in 1916, who helped discover DNA; John W Campbell, in 1910, arguably the greatest influence on science fiction ever; and Giovanni Domenico Cassini, in 1625, who discovered the Cassini Gap in the rings of Saturn, the broad black band in the 2004 Hubble telescope's picture below...