ESRT Page 2 Practice

Page 2 of the New York State Earth & Space Sciences Reference Tables (ESRT) is one of the most useful pages on the entire Regents exam. It contains two pieces of information you will return to again and again: the Solar System Data Table and the diagram of Generalized Nucleosynthesis in a Massive Star.

The Solar System Data Table organizes information about the Sun, planets, and other solar system bodies in columns and rows. Each row is a single object — the Sun, Mercury, Venus, Earth, Earth's Moon, Mars, Ceres, Pallas, Jupiter, Saturn, Uranus, Neptune, Pluto, and Eris. Each column is a property: Mean Distance from Sun (million km), Period of Revolution, Period of Rotation at Equator, Eccentricity of Orbit, Equatorial Diameter (km), and Axial Tilt (°). To use the table, find the row of the object you care about, slide your finger across to the column for the property you need, and read the value where they cross.

The eccentricity column tells you how stretched out an orbit is. A perfectly circular orbit has an eccentricity of 0. A long, narrow ellipse has an eccentricity close to 1. Among the planets, Mercury has the highest eccentricity (0.206) and Venus has the lowest (0.007). The dwarf planet Eris has the most eccentric orbit on the table at 0.436. Memorizing those extremes makes many Regents questions easier.

The axial tilt column reveals how a planet is oriented in space. Earth tilts at 23.49°, which is what gives us seasons. A few objects have extreme tilts — Venus is 177.4° (essentially upside down, which is why it rotates backward), Uranus is 97.77° (rolling on its side), and Pluto is 122.5°. Notice also that planets closer to the Sun have shorter periods of revolution: Mercury orbits in 88 days, while Neptune takes 163.7 years. Equatorial diameter shows that Jupiter (142,984 km) is the largest planet by far, more than 11 times the diameter of Earth (12,756 km).

The second feature on page 2 is the Generalized Nucleosynthesis in a Massive Star diagram. Nucleosynthesis means "making new atomic nuclei." Inside a massive star, nuclear fusion combines lighter elements into heavier ones, and the diagram shows that this happens in concentric layers — like an onion. The outermost, thickest layer is hydrogen, which fuses into helium. Just below that, helium fuses into carbon. Each deeper layer is hotter and contains heavier elements: carbon fuses to oxygen, oxygen fuses to silicon, and silicon finally fuses to iron in the core.

The duration table next to the diagram tells a dramatic story. Hydrogen fusion lasts about 7 million years, but each successive stage gets faster: helium fusion lasts ~700,000 years, carbon-to-oxygen fusion takes only 600 years, oxygen-to-silicon takes 6 months, silicon-to-iron takes just 1 day, and the final core collapse happens in 1/4 of a second. Iron is the last element a massive star can fuse. Once iron builds up in the core, fusion stops releasing energy and the star collapses, triggering a supernova. Every element heavier than iron in your body — gold in jewelry, iodine in your thyroid, zinc in your bones — was forged in such an explosion. When you look at this diagram on the ESRT, remember: the elements get heavier as you move toward the center, and lighter as you move toward the surface.