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After the icy giants form there’s not a lot of gas left for the terrestrial planets to accrete. Planets that are rocky like Mercury, Venus, Earth and Mars may take tens of millions of years to form after the birth of the star. The details of exactly where planets prefer to form in disks is still a mystery and an ongoing area of research.
- Clues from Our Past
- Looking to Our Future
- Building Our Knowledge of How Stars and Planets Begin
In cosmic phenomena, we see echoes of our distant past. Massive clouds of gas and dust condense into centralized protostars, that in turn emit powerful solar wind and bursts of radiation. A newborn star emerges from its molecular cloud nursery. Material left over from the star’s formation collapses into protoplanets. Each of these observations—now ...
Stars follow different paths as they age, determined by their mass, with the most massive burning their fuel exponentially faster. Smaller stars, like our Sun, live long lives. As they start to run out of hydrogen fuel in their core, they expand and turn red, becoming red giants. The byproducts of fusion collect in the core and, if the star is mass...
Our current understanding of how, when, and where stars and planets form and evolve is advanced through theory and observation. Data from current and next-generation telescopes will inform new computational models for stellar and planetary life cycles. These models are refined and may yield new theoretical discoveries which are in turn tested again...
Kepler’s First Law describes the shape of an orbit. The orbit of a planet around the Sun (or a satellite around a planet) is not a perfect circle. It is an ellipse—a “flattened” circle. The Sun (or the center of the planet) occupies one focus of the ellipse. A focus is one of the two internal points that help determine the shape of an ...
May 2, 2024 · The movement of Mars was problematic – it didn’t quite fit the models as described by Greek philosopher and scientist Aristotle (384 to 322 B.C.E.) and Egyptian astronomer Claudius Ptolemy (about 100 C.E to 170 C.E.). Aristotle thought Earth was the center of the universe, and that the Sun, Moon, planets, and stars revolved around it.
The degree of flatness of an ellipse is measured by a parameter called eccentricity. An ellipse with an eccentricity of 0 is just a circle. As the eccentricity increases toward 1, the ellipse gets flatter and flatter. A major problem with Copernicus’s theory was that he described the motion of the planet Mars as having a circular orbit. In ...
Jun 26, 2008 · Kepler's three laws describe how planetary bodies orbit the Sun. They describe how (1) planets move in elliptical orbits with the Sun as a focus, (2) a planet covers the same area of space in the same amount of time no matter where it is in its orbit, and (3) a planet’s orbital period is proportional to the size of its orbit (its semi-major ...
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Jul 29, 2023 · For instance, suppose you time how long Mars takes to go around the Sun (in Earth years). Kepler’s third law can then be used to calculate Mars’ average distance from the Sun. Mars’ orbital period (1.88 Earth years) squared, or P 2 P 2 , is 1.88 2 = 3.53 1.88 2 = 3.53 , and according to the equation for Kepler’s third law, this equals the cube of its semimajor axis, or a 3 a 3 .
