How old is the sun and planets

Tycho's observations of planetary motion were the most accurate of the time before the invention of the telescope! Using these observations, Kepler discovered that the planets do not move in circles, as years of "Natural Philosophy" had taught.

He discovered that they move in ellipses. A ellipse is a sort of squashed circle with a short diameter the "minor axis" and a longer diameter the "major axis".

He found that the Sun was positioned at one "focus" of the ellipse there are two "foci", both located on the major axis. He also found that when the planets were nearer the sun in their orbits, they move faster than when they were farther from the sun.

Many years later, he discovered that the farther a planet was from the sun, on the average, the longer it took for that planet to make one complete revolution. Here you see a planet in a very elliptical orbit. Note how it speeds up when it's near the Sun. Kepler's third law is the one that interests us the most. It states precisely that the period of time a planet takes to go around the sun squared is proportional to the average distance from the sun cubed. Here's the formula:.

Note that as the distance of the planet from the sun is increased, the period, or time to make one orbit, will get longer. Kepler didn't know the reason for these laws, though he knew it had something to do with the Sun and its influence on the planets. That had to wait 50 years for Isaac Newton to discover the universal law of gravitation.

Closer planets revolve faster, more distant planets revolve slower. The answer lies in how gravity works. The force of gravity is a measure of the pull between two bodies.

This force depends on a few things. First, it depends on the mass of the sun and on the mass of the planet you are considering. Through this technique, meteorites — bits of rock that have broken off from asteroids or comets in space and fallen to Earth — can be dated.

Since almost everything in our solar system formed around the same time, meteorites that reach Earth are, in all probability, the same age as our planet. He used samples of the Canyon Diablo meteorite that landed about 50, years ago in what is now the US state of Arizona, and using lead-lead dating came up with an estimated age range of 4.

Since then, other meteorites have also been used to find the age of Earth. Occasionally, a falling rock will be large enough to make it to the surface, becoming a meteorite. But we can do better than aggregating everything together! Sure, that gives a great overall estimate, but we think that, say, Earth and the Moon are younger than the meteorites by a little bit.

And finally, we have to sanity-check ourselves. All of this was predicated on the assumption that the ratio of U to U was the same everywhere in the Solar System. But new evidence within the last 10 years has shown this is likely untrue. The effected expect of background in the LUX detectors, including how radioactive material The signals seen by LUX are consistent with background alone. As elements decay over time, the reactant and product abundances change.

According to Gregory Brennecka ,. Since the s, or even before that, no one had been able to detect any differences [in uranium ratios]. But two years ago, a resolution was discovered : there's another element that plays a role. Curium, an element heavier and with a shorter half-life than even Plutonium, will radioactively decay into U, which explains the variations exquisitely. The uncertainties left over are only a few million years at most. Protoplanetary disks, which all solar systems are thought to form with, will coalesce into planets It's important to recognize that the central star, the individual planets, and the leftover primordial material which will, for example, become asteroids may all have variations in ages on the order of tens of millions of years.

So overall, we can say that the oldest solid material we know of in the Solar System is 4. In addition, we can't learn this by looking at the Earth itself; the rocks that are left over here are all older than that.

But the Sun, perhaps surprisingly, may be a little bit older, since its formation should pre-date the solid objects that make up the other components of the Solar System.

The Sun may be as much as tens of millions of years older than the oldest rocks in the Solar System, possibly approaching 4. The key, no matter what, is to look for the answer extra-terrestrially. Ironically, it's the only way to accurately know our own planet's age! This is a BETA experience. You may opt-out by clicking here. More From Forbes. Jul 23, , am EDT. Jul 15, , am EDT. Jul 8, , am EDT. Jul 1, , am EDT. Jul 20, , am EDT. Jul 19, , am EDT.

Jul 18, , am EDT. Jul 17, , am EDT. Jul 16, , am EDT. Edit Story.