where do planets come from?

it works like this. a very long time ago a mommy planet and a daddy planet met and fell in love. they did adult things in their bedroom, and a million years later mommy planet had a baby planet.

In a way, yes. But I don't think he was thinking of the correct way. There are a couple ways this could be argued:

1. When the universe was first created, there were tons of small stars that formed and died quickly. Now, matter cannot be created or destroyed and no planets were really present at this time because the stars were so small and so short-lived. This matter was changed, but is going to be reused. So the same matter that was in those stars is now in everything in the universe.

2. The matter that made our planets was left over matter from the sun... it condensed and formed planets, asteroids, and everything else in our solar system.

Then you have these special planets called "brown dwarfs" which some think are the left over cores from a star... probably a small star that burned out very quickly. And because it has such a low mass, there was no nova as a result.

Planets form usually through accretion, the gradual accumulation of mass due to gravitational attraction. In a solar system type setup, the closer the debris is to the protosun, or newly forming star, the heavier, and more dense the debris, because any liquids, or lighter elements would evaporate on contact, thus making it impossible for accretion to take place, and form an object large enough to become a planet. This theory is demonstrated in our own universe, because, the inner planets: mercury, venus, earth, and mars, are all very rocky (terrestrials), and are that way, because when our planets were forming, only heavier, and more dense debris could stay in their solid state when they were close to the sun. On the other hand, the Jovians: jupiter, saturn, uranus and neptune, are gas giants, because lighter elements in their liquid and gaseous states could only undergo accretian at farther distances from the sun, because it was cooler there. Back to your origional question, most planets do form from stars, but the way you are asking the question makes it seem like stars turn into planets, which is not true. However, much of the elements that make up the inner planets of our solar sysetm are formed inside of stars, as well as some outer planets.

Sort of. All the planets that are in our solar system was created from the mass of an exploding star. After a really long time, the mass starts to clump up together because of gravity. the smaller pieces may become planets and asteriods and such while the main concentration of mass can form a new star when dense enough to start nuclear fusion. Jupiter was close to becoming a star but didnt have enough mass.

Planets come from the same origins as do stars, according to conventional theory. The stars and planets emerge from gas and dust particles which are attracted to each other by gravity. The gas and dust required to do this is quite massive, and it takes a very long time for it to collect into sufficiently dense masses to become stars, planets and moons.

hes right in a way. wen a star explodes and go supernova, it releases all the components and gases that the star was composed of, leaving nebulae. tnebulae ar regions of gas that are know as "star forming areas". gravity can combine these gases and form stars or even planets

They get formed from protoplanetary disks!

actually your friend may be correct, especially all of the billions of crashes that occur between galaxies

Well, it depends on what you believe in spiritually.