"Could a person throw a basketball into orbit on the moon? No! You'd have to really launch it. Although it would depend somewhat on how high an orbit you wanted, the velocities involved are very high. Lets say you wanted to throw the ball clear off the moon. The escape velocity varies by the square root of the gravitational force. On earth, the escape velocity is 25,000 mph -- on the moon, however, it is still 10,000 MPH! LunarBBall limits your shot speed to 30 ft/sec or about 20 MPH -- quite a shortfall in speed to what you'd need. Conclusion: You'd still need a rocket!"
"Jupiter actually radiates heat like a very cold star. In fact, Jupiter is considered a 'proto star' by many scientists. If it had been given a little more mass as it formed . . . Well, just watch the movie '2010' to see what could have ( or could ) happen."
"Body mass varies as the cube of dimension, bone strength however, as the square of bone cross-section. So What? This is why a large animal, like and elephant, needs much thicker bones, proportionally, than a small animal, like a mouse. For you, this means that under the moon's 1/6 of earth's gravity, you could support your body's weight with very thin, narrow bones ( see the movie 'First Men on the Moon' for an example of a possible selenite, or moon-dweller). On Jupiter, however, you'd need massive bones to support your almost 3 times earth weight -- you'd probably put a Pro Football lineman to shame!"
"Our chemical rockets are actually rather marginal at getting us to orbit. You can't do it in one stage, you have to use multiple stages and to leave our solar system completely ( like Voyager did ) you need to use 'slingshot' effects from planetary gravitational fields. What if man had lived on Jupiter in its gravitational field of almost 3X that of Earth -- could we have make it into orbit? Maybe not. On a heavy enough planet, no chemical rocket could make it. For an exciting story of a heavy planet dwellers struggle to climb out of a horrendous gravity well read 'Heavy Planet', a short story you can find in many SF anthologies -- You'll like it!"
"If you saw the calibration sequence at the beginning of the game you'd know that the moon has 1/6 the Earth's gravity, while Jupiter's gravity is 2.87 times as great. But what about the other planets? Mercury's gravity is about 1/3 that of Earth's. Venus, Earth's twin, has just slightly less gravity ( .9 that of Earth's). Mars, like Mercury, has about 1/3 Earth's gravity. Saturn comes in at 1.32 times that of Earth. Uranus is .93 ( Earth, Venus, and Uranus have about the same gravity -- as do Mars and Mercury). Neptune 'weighs in' at 1.23 that of Earth. What about Pluto? Who knows, but the best guess right now is 1/500 of Earth's! That's right! The Moon may be more a planet than Pluto!"
"The moon is really big enough to be considered a planet -- it has over 1/4 of Earth's diameter and 1/6 its gravity. In fact, it is one of seven large satellites of the solar system. Can you identify the other 6? Anyway, the Moon is so large in comparison to its primary (Earth) that the Earth could easily be considered a 'binary planet' rather than a planet-satellite pair. Pluto appears to also be such a 'binary planet' with its moon Charon."
"The moon exerts enormous tidal forces on the Earth. These forces have shaped and continue to shape all life on earth. They are also slowing Earth's rotation. The fossil record shows that 100 million years ago, a day was only 22 hours long! If you want to read a couple of good essays on the moon's effect on us ( and what it might have been like without it) read Isaac Asimov's essays on the subject."
"LunarBBall in a simulation -- a rather simple one. It uses equations and empirical observations to simulate what it would really be like to play basketball in other places. As such, it is much more than a game! One of the very best things you can do with your computer is to run simulations -- they extend your body and mind into areas that you may never physically go. One of the most beautiful simulations is 'Dance of the Planets' by ARC, P.O. Box 1974, Loveland CO 80539 (Tele: 303-667-1168). A truly amazing and complex simulation; it simulates the solar system complete with comets, asteroids, etc. in the future, the present, or the past -- Truly wonderful and the only Space Travel I ( or perhaps even you) are likely to experience. Its well worth the price!"
"The solar system is not all that well understood. Why is the Earth's moon so large in comparison to Earth and where did it come from? Why does Venus have retrograde rotation (it rotates opposite the other planets)? What about Neptune with the large moon Triton in retrograde orbit? ( Six satellites have retrograde orbits! Why?) Why is Uranus' axis tilted over by 97 degrees? Pluto is out of sync with the other planets in a high inclination orbit. Why?"
"The Moon is actually moving away from the Earth over time -- its orbit is getting larger as the Moon speeds up. Phobos is doing just the opposite around Mars -- it is slowing down and spiraling inward to an eventual impact on Mars . . . in about 50 million years."
"Phobos orbits Mars in an extremely close orbit -- only one Mar's diameter away from the surface and moving extremely fast with an orbital period of only 1/3 a Martian day. This orbit seems rather like that of an artificial satellite (which has sparked wild conjectures by some)."
"The planets can be divided into three groups, Terrestrial, Jovian, and Pluto. Yup, Pluto is in a class by itself! The Terrestrial planets are the rocky inner ones -- Mercury, Venus, Earth, and Mars. The Jovian planets are gas giants with large amounts of hydrogen and helium in their atmospheres. They are of course, Jupiter, Saturn, Uranus, and Neptune. They all have rings, although Saturn's are by far the most spectacular."
"Why don't rockets take off straight up and keep going straight up? Because gravity can only rob velocity in the vertical direction. A rocket rolls and begins horizontal acceleration as soon as possible to hide as much velocity as possible from gravity. We have to take every advantage we can to make it to orbit -- for instance an equatorial launch gives us a little bit more velocity due to the earth's rotation -- it can be important. We use 2 or 3 stages to defeat the clutch of gravity with as light a fuel load as possible, etc. For a chilling tale of the physics of fuel consumption, read the very famous SF short story 'Cold Equations'."
"How much further could you throw a basketball on the moon vs. on earth? Try it and see!"
"Scientists think that there is a great swarm of comets in what is known as the 'Oort cloud' a light-year or so from the sun. Passing Stars disturb this cloud every few million years and send comets careening into the solar system. One such comet may have been responsible for the extinction of the dinosaurs. There seem to be other, nearer reservoirs of comets like those in the 'Kuiper disk' that seems to lie just beyond Neptune's orbit. Comets, and Asteroids, make the Solar system a dynamic, ever changing system!"
"Asteroids are mainly found in the asteroid belt between Mars and Jupiter -- but not always. There are 'inner asteroids' that pass close to earth. They come in three groups -- The 'Atens' whose orbits lie entirely within Earth's orbit, the 'Apollos' that cross Earth's orbit, and the 'Amors' whose orbits are outside that of Earth's. The 'Apollos' are a little scary -- they could collide with Earth. For instance in March of 1989, asteroid 1989FC passed within 600,000 km of Earth -- a distance barely outside of the Moons orbit! A collision in not likely but here's a thought to keep you up at night: a special 'Spacewatch' telescope on Kitt Peak finds several new 'close approaches' per month."
"What's the largest moon in the Solar System? Ganymede, a moon of Jupiter, which has twice the mass of our own Moon. Then comes Callisto only slightly smaller and about the same size as the planet Mercury. Then Io and Europa are next with sizes of about our own moon. These four moons, a
