How do scientists believe the Earth was created? Why is this controversial to some groups?
The nebular hypothesis is the leading theory as to how the Earth and solar system formed (note: not "created"). The only controversy is with non-non-scienitfic creationists.
The Nebular Hypothesis is the leading theory on how the sun, planets and Earth formed as one continuous process. See pic.
The early Earth was also modified by a collision of a "Mars-sized" porto-planet around 4.5 billion years ago. Called the "big thwack" or "big splat".
Most scientists agree that some variation on the Nebular hypothesis and the big thwack is probably correct, although there is still some work on the details.
The controversy is really with some creationist who feel that a supreme being must have "created" the Earth in a week or so and that this happened 6,000 years ago. Scientists would say it probably took millions of years for the Solar system to full form (including Earth) and that this happened 4.567 billion years ago. Scientists would also argue that this entire process probably went on without the need for postulating a "creator" to get it going.