Galileo's discovery that changed our views

On January 7^th 1610, Galileo Galilei made an observation through his small telescope that changed our understanding of the universe. Using his self made refractor telescope with an aperture just one inch in diameter with a magnification of 15X, Galileo pointed his telescope to the bright planet Jupiter. The planet Jupiter showed up in the narrow of 15minutes of arc field of the telescope, accompanied by three satellites, Io was observed on 8^th January as his crude instrument was unable to separate Io and Europa the previous night.

There was no previous records of observations made of Jupiter through telescope and Galileo was in uncharted territory. Galileo first took these 4 objects as stars and continued his observations. The movement of Jupiter with respect to these “stars” made Galileo to think that maybe Jupiter has a retrograde loop. As he continued to track Jupiter, he observed that Jupiter did not move much with respect to other stars apart from the 4 “stars” that were close to Jupiter. One more puzzling observation was that these 4 “stars” always stayed close to the planet.

After several nights of observations Galileo came to the conclusion that these 4 objects were carried along by Jupiter and they are moons of Jupiter. This had a profound impact on our way of looking at the universe. This observation gave the Copernican theory more ground.

Galileo gave the moons of Jupiter roman numbers I,II,III and IV. The names suggested by Simon Marius is what we use now. Io (I), Europa (II), Ganymede (III) and Callisto (IV). The moons are called Galilean moons in honour of Galileo.

Here is a copy of Galileo notes translated

Credit: NASA

Centuries later we sent spacecraft to Jupiter and also took pictures of the Jovian moons. Here are close up photos of the moons and also few facts about them.

Io

Credit: NASA/JPL/University of Arizona

Io is the closest of the Galilean moons which orbits the planet at a distance of 421000km. Io is little bigger than our earth's moon. Io has a radius of 1821km, earth's moon has a radius of 1738km. Io goes around Jupiter in 1.7days. Io is the most volcanically active moon in our solar system. One of the reason for this high activity is that Io is affected by gravitation of Jupiter and high tidal forces make molten interior escape through the gaps created from the distortions caused by the tidal forces.

Europa

Credit: NASA/JPL/Ted Stryk

Europa is the second moon from Jupiter and is little smaller than our moon. The radius of Europa is around 1560km. It orbits the planet at a distance of 670000km and completes one rotation in 3.5days. The surface is covered with frozen salt water and scientists think that with the eccentric orbit of Europa there may be places where it may be possible for water to exist.

Ganymede

Credit: NASA/JPL/Ted Stryk

Ganymede is the largest moon in the solar system, larger than the planet Mercury. The radius of Ganymede is 2631km and that of Mercury is 2439km. Ganymede orbits the planet Jupiter 1070000km and completes on orbit every 7.15days. This is the only moon to be known to have magnetosphere and also its been thought the moon may have a salt water ocean that is trapped under the ice surface.

Callisto

Credit: NASA/JPL/Ted Stryk

Callisto is the last of Galilean moons and also the farthest from the planet Jupiter. Callisto orbits the planet at a distance of 1882000km and completes on rotation around the planet in 16.6days. The moon Callisto is also the third largest moon in the solar system with a radius of 2410km almost the size of Mercury. Callisto is among the most cratered objects in solar system. Scientists think that the core could have frozen as it formed and no geological activity has taken place from the past 4 billion years.

Jupiter is easy to spot these days. Just after sunset if we look you, Jupiter will be shining bright in the Zenith. No star in the region is as bright as Jupiter. The moons of Jupiter can easily be seen even with a pair of binoculars.

The Hindu : NATIONAL / KARNATAKA : Don't make light of it, say amateur astronomers

The Hindu : NATIONAL / KARNATAKA : Don't make light of it, say amateur astronomers

Saturn in close cut

IMAX IN A BASEMENT

outsideinthemovie.com/​

Not-for-profit animated IMAX film in early production by a single filmmaker. Visit the site to make a tax-deductible contribution to support the film. I hope to present this clip at the international IMAX show (GSCA Expo) next month.

I'm very excited to present the first test from "Outside In" that actually represents real footage in progress from the film. Camera moves are still being tweaked and this is cropped version as IMAX-sized stuff does not play well online. But thanks to the new version of Adobe After Effects, "Outside In" can be made as I have always envisioned.

Much thanks to everyone who has supported and contributed to this. This is the beginning, just a taste of incredible things to come.

This is fly-through of this photograph - photojournal.jpl.nasa.gov/​catalog/​PIA11141 - only a little brightness and contrast has been made to balance the moons with saturn's body. Do note that several thousand layers of many Cassini photographs were animated to make the fly-through work without any 3D CGI. The saturation is off due to lack of Flash Player ICM support.

This is still a work-in-progress and it's an art film, not a science film, but as new image data comes down I will tweak this shot for improved accuracy.

Milky Way Rising from Australia

Glory in the Sky: New Satellite Set to Monitor the Sun and Reflected Heat to Determine Climate Effects

The solar forecast calls for sluggish times ahead, according to scientists in Boulder, Colo.—which could have a cooling effect on Earth. A better understanding of solar processes and their climatic impacts will be key to understanding how far such quiescence could go to counteract global warming caused by pollution from fossil fuels.

There's little doubt the sun's been in a funkever since solar cycle 23 wound down in 2007. (Astronomers began to number the solar activity cycles in 1755.) The ramp-up to the peak of the next cycle is taking longer than expected and has been feeble, with precious few sunspots.

Normally, at the apex of each 11-year solar cycle—for cycle 24 it should occur around 2013—the sun's surface becomes especially frenetic, erupting into a climax of sunspots and flares. The outbursts can bombard the planets with gusts of highly charged solar wind, which triggers effects on Earth ranging from spectacular aurorae to interference with communications networks and even—in the worst cases—disruptive surges in power grids.

As the sun pushes toward the height of cycle 24, we'll still see a rise in solar activity, predicts Tom Woods, a solar physicist at the University of Colorado at Boulder'sLaboratory for Atmospheric and Space Physics (LASP), but "I think you can say with pretty fair confidence we're going to have a low maximum."

Predictions of global cooling became popular among climate change contrarians during the unexpected pause between solar cycles 23 and 24 and haven't completely subsided. But the degree to which a quiet sun could chill Earth, especially in the face of pollution that's warming the planet, is uncertain. Solar researchers are increasingly eager to quantify the sun's role, given the global importance of the question.

E=mc²: Einstein explains his famous formula

Controversy Over "Possible" Asteroid Collision

This week's ridiculousness began when a group of Russian scientists released a study in which they determined that the asteroid Apophis (which, by the way is pronounced like you are saying "a blow fish" but with a mouth full of marshmallows) had a significant chance of impacting the Earth in the year 2036.

Never mind the fact that NASA determined long ago that there was merely a 1 in 250,000 chance of such an impact. To put this into perspective, I am about as likely to attend a major league baseball game and catch a ball from the stands. Twice.

So why all the fuss? Well, the 900 foot long asteroid is going to pass within 20,000 miles of Earth -- which is extremely close by the way -- in 2029. During this pass there is an extremely unlikely chance that it could pass through what is known as a key hole. Key holes are regions of space that have a specific gravitational potential that would cause a passing object to eventually (in this case seven years later) impact our planet.

This particular keyhole is about 2000 feet in diameter, which is only slightly larger than Apophis itself. And considering that the orbital mechanics of the rock are likely to change, even if ever so slightly, between now and then it is extremely unlikely that it would pass through the key hole.

And even if the asteroid does pass within the keyhole? NASA researchers also point out that the gravitationally bound object is likely to break apart long before it makes it back to Earth in 2036. So it would still miss us anyway.

But, just to put your minds even further at ease, should the asteroid be determined to be on its way here, NASA is prepared to stop it. Basically they would just slam probe into the asteroid to knock it slightly off its course, sending it past Earth. They have already demonstrated this ability with the Deep Impact probe which impacted the comet Temple 1 in 2005.

On the flip side, many researchers are excited about the close pass in 2029, and see it as an opportunity to conduct detailed studies of the object. So there you have it, no need to worry at all.