Transcript Day_31
ASTR-1010 Planetary Astronomy Day - 31 Size As Viewed From Earth Course Announcements Homework Chapter 9: Due Wednesday April 13. Exam 3: Will be returned on Friday. The last 1st Quarter moon observing nights are: Tuesday (April 20) & Thursday (April 22) 8:00 pm both nights. Exam 4 question Looking for something different? • ASTR-3005/3006 • ASTR-3030/3031 • Observational Astronomy • 1 hr lecture + 1 hr lab • Dr. Buckner • Prereq: Astr 1010 or 1020 ===================== Constellations and stars of the night sky; setup, align and use various types of telescopes. Hands-on use of APSU observatory. • Methods & Instrumentation • 2 hr lecture + 1 hr lab • Dr. Smith • Prereq: Phys 2020 or 2120 ===================== Instruction on the techniques of modern astronomy and use of instrumentation. Hands-on experience at the APSU observatory. Chapter 9 Lecture Outline Worlds of Gas and Liquid – The Giant Planets The Giant Planets • Jupiter and Saturn: mainly hydrogen and helium. • Uranus and Neptune: have much more water. • All these planets probably have a core of dense materials. Jupiter & Saturn Jupiter: NASA/JPL/University of Arizona Saturn: NASA and E. Karkoschka (University of Arizona) Uranus & Neptune Uranus Neptune: both images NASA Jet Propulsion Laboratory (NASA-JPL) Characteristics of the Giant Planets • Called giant planets because of their mass: from 15 Earth masses (Uranus/Neptune) to 300 (Jupiter). • No solid surfaces: we just see the cloud layers in the atmospheres. • Rapid rotation. • Strong magnetic fields. Cloud Patterns – Jupiter and Saturn Jupiter • Strong dark and light bands. • A long-lasting giant storm (Great Red Spot). • Many smaller storms. • Colors indicate complex chemistry. Saturn • Similar to Jupiter, but less pronounced. Cloud Patterns – Uranus and Neptune Uranus/Neptune • Almost featureless as viewed from Earth. • More detail seen from spacecraft or infrared observations from the Hubble Space Telescope. • Weak banding. • Small, scattered bright or dark clouds. • Transient large storms (Great Dark Spot on Neptune). Composition • Mainly light elements (hydrogen/helium). • Jupiter’s composition like that of the Sun (71% H, 27% He). • Biggest difference is the amount of massive elements. • Saturn has somewhat more than Jupiter. • Uranus/Neptune have larger fraction of massive elements. Probing the Atmospheres • Density, composition, and circulation patterns vary with height. • Temperature, pressure increases downward. • Different appearance of planets from different heights of cloud layers. • Example: Clouds on Jupiter. – Ammonia (NH3) at T = 133 K. – Ammonium hydrosulfide (NH4SH) at T = 193 K. • Strong winds, storms, and jet streams. Cloud Layers Winds and Storms • Rapid planetary rotation results in strong Coriolis forces. This imparts a rotation to storms. • Most extreme winds are in Saturn’s atmosphere (1650 km/hr). • Alternating east/west winds make banded clouds on Jupiter. • Circulation pattern differs from planet to planet in ways not understood. Wind Speeds Internal Heat • All but Uranus have significant internal heat. • Jupiter is hotter than it would be just from sunlight. • Jupiter radiates about 65% more energy than it receives from the Sun. • Heat flows from the hot interior outward. • Heat has a big effect on the global circulation patterns. The Zones and Belts are convection regions Jupiter rotates faster at the equator than at the poles Polar Rotation Period 9 hr 55 min 41 sec Equatorial Rotation Period 9 hr 50 min 28 sec