How did scientists find out that the solar system was formed?

Answer 1

All inner planets, as well as Mars, Jupiter and Saturn are well known since prehistorical times by direct visual sight.

These planets were subject of observation, and the Sumerians were the first to study these planets as a science (Astronomy), and as a base to predict the future (Astrology).

Jupiter and Saturn's movements were systematically observed by the Babylonianastronomers, from the 7th or 8th century BC.

There is a dispute about who first acknowledged Uranus as a planet, not as a star as previously thought.

Sir William Herschel presented his conclusions to the Royal Society in 1783, but Russian astronomer and mathematician Anders Johan Lexel (born in Sweden) was the first to defend Uranus was a planet, and he also calculated its orbit around the Sun, when Herschel still considered Uranusa comet.

However, Uranus was formally discovered by Herschel, using for the first time an optical telescope to find a new planet.

Neptune was the first planet discovered by mathematical prediction rather than by telescope obervation. Its discovery is also disputed between Le Verrier and Johann Galle...

The dwarf planet Pluto, considered the nineth planet of the Solar System on his own merit until 2006, was discovered only in 1930 by the young astronomer Clyde Tombaugh, died in 1997 at age 90.

It was the first time a planet was discovered using Photography. Tombaugh used a new technology to compare photographs from the sky taken at different times, called a «Blink Comparator».

Part of Tombaugh ashes will orbit Pluto, sent inside a small probe orbiter carried aboard the New Horizons spacecraft mission, which will arrive Pluto in 2015).

Although the International Astronomical Union keeps insisting Pluto is not a planet, the scientifical community is not unanimous on this formal decision taken after the discovery of Eris, a Kuiper Belt object larger and heavier than Pluto.

Asteroids and other trans-Neptunian objects are not discussed here.

(But it would be an interesting question to answer!)

Answer 2

Scientists believe a large gas cloud in space was condensed into what we now call the sun. Chunks of this cloud flew into orbit around the sun and eventually condensed into planets and that that was how the solar system was made - and they used telescopes, satellites, and the moon to find it out.

Answer 3

There are multiple ways in which exoplanets can be discovered/obsereved. The four primary methods used by astronomers are as follows;
1. Doppler
A doppler shift reveals a change in frequency from something moving towards/away from an observer. Our most advanced doppler velocity variations of stars of less than two meters per second which occurs because orbiting planets 'tug' on their host stars causing them to move slightly, one of stephan hawkings examples was a hammer thrower in the Olympics, as the hammer moves, the athlete wobbles and the two move around each other

2. Transits
This method requires then observing of the host star as the planet crosses directly between the star and earth allowing us to see the star dim. In order to confirm that it is a planet we must observe three transits in a row to ensure that it is not a random fluke. And keep in mind that the dimming is like having 10,000 light bulbs and then taking ONE of them away.
The Kepler space telescope detects planets in this manner and you can get an app on your smartphone called zooniverse which allows you to look at pictures of the thousands of stars kepler has imaged to look for this dimming, which is awesome because it means that you could discover an exoplanet.

3. Timing variations
This method can only be used to detect other planets in a system with at least one known planet. This method works by looking for variations in known planets orbits caused by the tugging of other planets in the system, this effect usually ranges from between a few seconds too a few minutes.

4. Direct imaging
This is at the absolute edge of current technological capabilities as it requires a coronagraph (something that blocks the light of the planets sun) thereby allowing astronomer to directly observe the exoplanet