Your tour of the solar system begins with this dramatic overview. The sun, which contains 99.85 percent of all matter in the solar system, dominates the planets, which are seen rotating precisely in proportion to one another—Jupiter fastest, Venus slowest. Their relative orbital speeds are also accurately reproduced, with Mercury—closest to the sun—rounding that star every 14.5 seconds, corresponding with its actual 88-day orbit.

You might start by clicking the sun and working outward, or you can create your own planet-skipping itinerary. With each planetary visit—and on side trips to the asteroids or a passing comet—you’ll discover the latest information about our cosmic neighbors.

But before you begin your travels, pause to watch the solar system in action. Circles within circles, wheels within wheels, the planets, moons, comets, and asteroids whirl about the sun like flywheels in a cosmic timepiece.

Some scientists believe that every molecule can be traced to the Big Bang—the moment of creation when the entire universe exploded from a single, unimaginably dense point. As the universe expanded and its elements cooled, the dusty residue began to draw together into vast molecular clouds which, in turn, clumped together, compressed under their own gravity, and ignited as stars.

About 4.6 billion years ago, halfway out on one spiral arm of the galaxy we call the Milky Way, our developing sun emerged from a condensing molecular cloud. The star-to-be was surrounded by a disk of dust and ice, which over a period as brief as 100,000 years clumped together to form asteroid-size planetesimals. Then began a cosmic game of billiards, as the ever-growing fragments collided, shattered, and then reassembled themselves into ever larger bodies. The infant solar system was chaotic, but from the carnage nine major bodies, the planets, emerged.

Soon, the developing sun accumulated so much mass it ignited, becoming a full-fledged star. The explosion of energy emitted at the sun’s birth flew in all directions, clearing gas and dust particles from among the planets. Nine planets saw their first sunrise.

The sun’s heat most likely kept ice from covering the inner planets, so Mercury, Venus, Earth, Mars, and the rubble of the asteroid belt grew mostly from rocky materials. Farther out, abundant ices combined with rocks to form the large cores of Jupiter, Saturn, Neptune, and Uranus. Their substantial gravity enabled them to attract huge amounts of gas, creating the giants of the solar system. And beyond them, the tiny double-planet team of frozen Pluto and its satellite Charon, their unconventional orbit periodically taking them inside that of Neptune, skirt the fringes of the family of planets.

It’s clear that ours is not the only star with planets around it—ground-based telescopes have found evidence of large, Jupiter-like planets beyond our solar system. A few of these planets orbit at critical distances from their stars at which temperatures might be hospitable to life as we know it. The more we learn about our neighbor planets, and why they are the way they are, the better we’ll understand the possible conditions on planets we discover far beyond our own solar system.