Which planet rotates so fast that its day is only 10 hours long?

Both Jupiter and Saturn have days that last about 10 hours. Jupiter has a period of 0.410 earth days or about 9.84 hours and Saturn has a period of 0.426 earth days or about 10.224 hours.

What is the Astronomical Unit?

When describing distances on the scale of our Solar System, conventional units of measure are not conveniently sized. Miles are too small, and light years are too large, to permit easily compared numbers. For example, the distance between the Sun and Earth is about 93,000,000 miles; between the Sun and Pluto is about 3,700,000,000 miles. Comparing those two numbers, it is not easily seen that Pluto is about 40 times as far from the Sun as Earth is.


The Astronomical Unit (AU) represents a distance of Earth's average distance to the Sun, or about 93,000,000 miles.

How did planet Neptune get its name?

In Roman mythology Neptune was the god of the Sea.

After the discovery of Uranus, it was noticed that its orbit was not as it should be in accordance with Newton's laws. It was therefore predicted that another more distant planet must be perturbing Uranus' orbit. Neptune was first observed by Galle and d'Arrest on 1846 Sept 23 very near to the locations independently predicted by Adams and Le Verrier from calculations based on the observed positions of Jupiter, Saturn and Uranus. An international dispute arose between the English and French (though not, apparently between Adams and Le Verrier personally) over priority and the right to name the new planet; they are now jointly credited with Neptune's discovery. Subsequent observations have shown that the orbits calculated by Adams and Le Verrier diverge from Neptune's actual orbit fairly quickly. Had the search for the planet taken place a few years earlier or later it would not have been found anywhere near the predicted location.

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What is the hottest part of Sun?

The center of the sun is the hottest part (at around 15 million Kelvins, or 27 million degrees Fahrenheit). The temperature then drops to 5,800 K (10,000 degrees F) at the visible surface, although the corona (the part just above the surface, where solar flares are), can get much hotter (2 million K, or 3.6 million degrees F).

What is the difference between cathode rays and beta rays?

cathode 'rays' were observed in electrical experiments because of their fluorescent effect near a negatively charged plate (called the cathode) in a vacuum. They were only later found to be negatively charged electrons emitted from negatively charged plates and accelerating toward positively charged ones. (Like charges repel, unlike charges attract.)

Beta 'rays' were first observed being emitted from certain unstable (radioactive) isotopes, and behaved unlike the alpha and gamma radiation also found in radioactivity. It wasn't until later that both alpha and beta 'radiation' were discovered to actually be particles; only gamma rays consist of true electromagnetic radiation. Beta 'rays' are actually electrons ejected from decaying neutrons, and are now more often referred to as Beta emission or Beta particles. 

So electrons can be described differently, not based on WHAT they are but HOW they are created or observed.

How fast do electrons travel when moving as an electrical current through copper wire?

The actual velocity of electrons through a conductor is measured as an average speed called drift velocity. This is because individual electrons do not traverse straight line paths in conductors, instead they move in a random zig-zag motion, changing directions as they collide with atoms in the conductor. Thus, the actual speed of the electrons through the conductor is very small in the direction of current.

For example, the drift speed through a copper wire of cross-sectional area 3.00 x 10^-6 m², with a current of 10 A will be approximately 2.5 x 10^-4 m/s or about a quarter of a milimeter per second.