Bell Ringer 2/19/20161. How did Johannes Kepler contribute to the

Scientific Revolution?2. Who’s theory did Kepler disprove?

Kepler’s DiscoveryGerman astronomer who discovered three major laws of planetary motion:

(1) the planets move in elliptical orbits with the Sun at one focus; (2) the time necessary to traverse any arc of a planetary orbit is

proportional to the area of the sector between the central body and that arc (the “area law”); and

(3) there is an exact relationship between the squares of the planets’ periodic times and the cubes of the radii of their orbits (the “harmonic law”). • He regarded them as celestial harmonies that reflected God’s design

for the universe. • Kepler’s discoveries turned Nicolaus Copernicus’s Sun-centered

system into a dynamic universe, with the Sun actively pushing the planets around in noncircular orbits.

Kepler Inspires Today!• In 2001 NASA created a mission that honors

astronomer Johannes Kepler!• The Kepler Mission is a NASA Discovery

Program for detecting potentially life-supporting planets around other stars. All of the extrasolar planets detected so far by other projects are giant planets, mostly the size of Jupiter and bigger. Kepler is poised to find planets 30 to 600 times less massive than Jupiter.

How the Kepler Mission Works…• By a method known as the transit method of planet

finding. When we see a planet pass in front of its parent star it blocks a small fraction of the light from that star. When that happens, we say that the planet is transiting the star.

• If we see repeated transits at regular times, we have discovered a planet! From the brightness change we can tell the planet size. From the time between transits, we can tell the size of the planet's orbit and estimate the planet's temperature. These qualities determine possibilities for life on the planet.

What is Kepler??• The Kepler satellite has a 0.95-meter diameter telescope

that is a photometer having a field of view a bit over 10 degrees square (and area of sky the size of about two open hands). It is designed to continuously and simultaneously monitors brightnesses of 100,000 stars brighter than 14th magnitude in the constellations Cygnus & Lyrae.

• To detect an Earth-size planet, the photometer must be able to sense a drop in brightness of only 1/100 of a percent. This is akin to sensing the drop in brightness of a car's headlight when a fruitfly moves in front of it! The photometer must be spacebased to obtain this precision.

Kepler was launched in March 2009• The overall size is about 2.7

meters (nine feet) in diameter and 4.7 meters (15.3 feet) high.

• The total mass at launch was 2,320.1 pounds

• The Kepler Mission life cycle cost is approximately $600 million. This includes the design, construction, launch and operation of the spacecraft as well as the scientific analysis of the data.

Kepler-425b• In a press conference (2015 July 23), NASA's

Kepler team announced discovery of planet Kepler-452b which has the closest match of planet characteristics to Earth: 60% larger than Earth, orbiting a Sun-like star in a 385 day orbit period, that puts it in the star's habitable zone. [Kepler confirmed planet count is now 1030.]

Comparing Informational Texts

• Read the 2 passages on the handout.• Using the reading, answer the multiple choice

questions • After answering the questions, complete the

essay. Pay close attention to what the prompt is asking and be sure to respond appropriately!