View
79
Download
1
Category
Tags:
Preview:
DESCRIPTION
Planet Venus
Citation preview
Ancient astronomers didn’t really know what Venus was. They knew it was an object that moved in the sky from night to night, sometimes being obscured by the glare of the Sun. But it wasn’t until Copernicus developed his model of the Solar System that
placed the Sun at the center, and the planets orbiting it. At that point, both Venus and Earth were recognized to be planets.
Galileo pointed his telescope at Venus in 1610, and confirmed Copernicus’ theory by showing that Venus went through distinct phases, just like the Moon. The phases matched the predictions made by Copernicus, and demonstrated that Venus was really a
planet, orbiting the Sun and not the Earth.
This model was confirmed even more when Venus made a transit across the surface of the Sun on December 4, 1639. The most
recent transit of Venus happened in 2004, and the next one will occur in 2012.
WHO DISCOVERED VENUS?
Venus is a beautiful planet at night. It is one of the brightest objects in the night sky. Only the moon is brighter
WHY VENUS?
• Venus is very bright in the sky “Evening star” “Morning star”
Fun Fact!
The ancients named Venus after the goddess of love and beauty because it
is the brightest planet.
Early civilizations thought Venus was two different bodies, called Phosphorus and
Hesperus by the Greeks, and Lucifer and Vesper by the Romans. This is because
when its orbit around the Sun overtakes Earth’s orbit, it changes from being visible after sunset to being visible before sunrise.
Mayan astronomers made detailed observations of Venus as early as 650 AD.
MORNING STAR AND THE EVENING STAR
THE PLANET VENUS
• Venus is the planet nearest to Earth, sometimes approaching to within 40 million km
• The orbit of Venus is nearly circular at a distance of 108 million km (0.72 AU)
• Venus can get as close as 40 million km from the Earth. This is called an inferior conjunction every 584 days, on average.
Mass: 4,867,320,000,000,000 billion kg (0.815 x Earth)Equatorial Diameter: 12,104 kmPolar Diameter: 12,104 kmEquatorial Circumference: 38,025 kmKnown Satellites: noneNotable Satellites: noneOrbit Distance: 108,209,475 km (0.73 AU)Orbit Period: 224.70 Earth daysSurface Temperature: 462 °CFirst Record: 17th century BCRecorded By: Babylonian astronomers
PLANET PROFILE
Venus looks very bright to the naked eye and even a
small telescope shows that Venus goes through phases
like the MoonThe surface of Venus is
always obscured by a very dense cloud cover
Reflects 70% of the sunlight
Various bands are visible in different wavelength light
APPEARANCE OF VENUS
Enhanced picture of Venus shot through a violet filter by the Galileo spacecraft
Venus appears to go through phasesDifferent from Moon because distance changes drastically
PHASES OF VENUS
8
12,102 km in diameter(12,756 km
for Earth) 82% the mass
of Earth Similar density,
5.3 g/cm3 (5.5 g/cm3 for Earth)
Venus takes 2,243days to
rotate on it axis and it rotates the opposite direction
of Earth
Venus is nearly the same size as Earth Venus takes 223
days to orbit the Sun
BASIC PROPERTIES OF VENUS
9
The atmosphere of Venus causes a very high surface temperature and gives the surface a perpetual red twilightThe weather at the surface is hot, dry, calmThe pressure at the surface is 90 times the Earth’s atmospheric pressure
THE ATMOSPHERE OF VENUS
Gas %Carbon Dioxide (CO2)
95.3
Nitrogen (N2)
2.7
Argon (Ar)
1.6
Oxygen (O2)
0.15
Neon (Ne)
0.0003
The surface temperature of Venus is 700 K
800 degrees FahrenheitCaused by the greenhouse effect
Venus has 1 million times more CO2 than Earth
Sunlight that diffuses through the atmosphere heats the surface and the CO2 acts as a blanket
The surface heats up until the radiation of heat is the same as the absorption of heat from the SunThe dense atmosphere makes the temperature the same everywhere on the surface of Venus
Little weather
SURFACE TEMPERATURE OF VENUS
The first successful flyby of the Planet Venus was accomplished by Mariner 2 in 1962.
In 1970, the Soviet Venera 7 lander became the first probe to return data from the surface of Venus. Later Venera landers would
return images from the surface.
America sent two spacecraft to the planet in 1978. The Pioneer Venus Orbiter went into orbit around the planet, while the Pioneer Venus Multi-Probe deployed four atmospheric entry
probes to investigate the atmosphere.
The twin Vega spacecraft each deployed a surface lander and an instrumented atmospheric balloon in 1985.
The American Magellan mission, launched on the Space Shuttle in 1989, used a radar system to create high-resolution maps of the
planets surface.
Launched in 2005, the European Venus Express mission continues to orbit the planet.
THE EXPLORATION OF VENUS
The Magellan mission to Venus was launched May 4, 1989 and arrived at Venus on August 10, 1990Magellan used high resolution radar to map the
surface of Venus through the opaque cloudsMagellan worked for 4 years and mapped 98% of
the surface of Venus
THE MAGELLAN MISSION TO VENUS
13
False color picture of Venus constructed from radar images from the Magellan space craft
The Magellan data can be processed into 3-D views of the surface of Venus
THE SURFACE OF VENUS
3-D view of three impact crater on the surface of Venus
The largest crater on Venus is the Mead Crater
CRATERS ON THE SURFACE OF VENUS
The Mead Crater - 280 km in diameter
Larger than the largest crater on Earth
Computer generated 3-D view of Sif Mons using data from Magellan
Venus is a planet with wide-scale volcanic activityIn the lowland plains, lava renews the surface and erases cratersThere are many volcanoes associated with surface hot spots
VOLCANOES ON VENUS
• The largest volcano on Venus is Sif Mons
3 km high, 500 km across
Caldera is 40 km across
• These volcanoes result from magma reaching the surface
• Pressure under the surface can cause bulges called coronae
Venus rotates counter-clockwise:Also known as retrograde rotation. A possible reason might be a collision in the past with an asteroid or other object that caused the planet to alter its rotational path. It also differs from most other planets in our solar system by having no natural satellites.
FACTS ABOUT VENUS
www.scientificamerican.comwww.universetoday.com
www.space-facts.comwww.historicspacecraft.com
REFERENCES
LECTURE 11
18
Recommended