The
surface of Venus was scanned with radar waves beamed from orbiting space probes
to produce this image. The colors are based on photos taken by probes that
landed on Venus. Image credit: NASA
NASA's
Return to Venus - Director's Cut
Venus' dazzling beauty at night
explains its name. It is named for the Roman goddess of love and beauty.
A
1979 Pioneer 6 Venus image of Venus clouds seen in view of Venus Maat Mons
volcano.ultraviolet.
At first glance, if Earth had a
twin, it would be Venus. The two planets are similar in size, mass, composition,
and distance from the Sun. But there the similarities end. Venus has no ocean.
Venus is covered by thick, rapidly spinning clouds that trap surface heat,
creating a scorched greenhouse-like world with temperatures hot enough to melt
lead and pressure so intense that standing on Venus would feel like the pressure
felt 900 meters deep in Earth's oceans. These clouds reflect sunlight in
addition to trapping heat. Because Venus reflects so much sunlight, it is
usually the brightest planet in the sky
Only radar
can penetrate Venusıs thick clouds to reveal its topography (blues are low
areas; tans are high areas). Aphrodite Terra, a bright highland roughly the size
of Africa, winds across Venusıs southern hemisphere (false-color image data
from Magellan, Arecibo Observatory, Pioneer Venus, and Venera). (Right, top)
Venusıs thick clouds of carbon dioxide produce a ³runaway greenhouse effect.²
The Y-shaped cloud patterns indicate wind speeds up to 500 km per hour in the
upper layers of the atmosphere (Pioneer Venus near-ultraviolet image). (Right,
center) This cluster of large craters in an area the size of Michigan range in
diameter from 50 to 37 km (Magellan).
Bright areas of ancient lava
blanket the flanks of the 6-km-high volcano Maat Mons. The vertical scale in
this image has been exaggerated 23 times to enhance small features and aid
analysis of the area. The color is simulated based on data by the Soviet Venera
13 and 14 spacecraft (Magellan). (Right, bottom) Seven steep-sided and
flat-topped domes of lava have oozed onto the plains east of Alpha Regio. They
average 25 km in diameter with maximum heights of 750 meters (Magellan).
Although we cannot normally see through Venus' thick
atmosphere, NASA's Magellan mission to Venus used radar to image the surface,
and Galileo used infrared mapping to view mid-level cloud structure.
Like Mercury, Venus can be seen
periodically passing across the face of the Sun. These transits of Venus occur
in pairs with more than a century separating each pair. Since the telescope was
invented, transits were observed in 1631, 1639; 1761, 1769; and 1874, 1882. On
June 8, 2004, astronomers worldwide saw the tiny dot of Venus crawl across the
Sun; the second in this pair of early 21st-century transits will occur June 6,
2012.
The atmosphere consists mainly of
carbon dioxide, with clouds of sulfuric acid droplets. Only trace amounts of
water have been detected in the atmosphere. The thick atmosphere traps the Sun's
heat, resulting in surface temperatures over 470 degrees Celsius (880 degrees
Fahrenheit). Probes that have landed on Venus have not survived more than a few
hours before being destroyed by the incredibly high temperatures.
The Venusian year (orbital
period) is about 225 Earth days long, while the planet's rotation period is 243
Earth days, making a Venus day about 117 Earth days long. Venus rotates
retrograde (east to west) compared with Earth's prograde (west to east)
rotation. Seen from Venus, the Sun would rise in the west and set in the east.
As Venus moves forward in its solar orbit while slowly rotating
"backwards" on its axis, the cloud-level atmosphere zips around the
planet in the opposite direction from the rotation every four Earth days, driven
by constant hurricane-force winds. How this atmospheric "super
rotation" forms and is maintained continues to be a topic of scientific
investigation. About 90 percent of the surface of Venus appears to be recently
solidified basalt lava; it is thought that the planet was completely resurfaced
by volcanic activity 300 to 500 million years ago.
Sulfur compounds, possibly
attributable to volcanic activity, are abundant in Venus' clouds. The corrosive
chemistry and dense, moving atmosphere cause significant surface weathering and
erosion. Radar images of the surface show wind streaks and sand dunes. Craters
smaller than 1.5 to 2 kilometers (0.9 to 1.2 miles) across do not exist on
Venus, because small meteors burn up in the dense atmosphere before they can
reach the surface.
More than 1,000 volcanoes or
volcanic centers larger than 20 kilometers (12 miles) in diameter dot the
surface of Venus. Volcanic flows have produced long, sinuous channels extending
for hundreds of kilometers. Venus has two large highland areas:
Ishtar Terra, about the size of
Australia, in the north polar region; and Aphrodite Terra, about the size of
South America, straddling the equator and extending for almost 10,000 kilometers
(6,000 miles). Maxwell Montes, the highest mountain on Venus and comparable to
Mount Everest on Earth, is at the eastern edge of Ishtar Terra.
Venus has an iron core about
3,000 kilometers (1,200 miles) in radius. Venus has no global magnetic field,
though its core iron content is similar to that of Earth, Venus rotates too
slowly to generate the type of magnetic field that Earth has.
Venus: Facts &
Figures
Discovered By
Known by the Ancients
Date of Discovery
Unknown
Average Distance from the Sun
Metric: 108,208,930 km
English: 67,237,910 miles
Scientific Notation:
1.0820893 x 108 km (.723332 A.U.)
By Comparison: 0.723 x
Earth
Perihelion (closest)
Metric: 107,476,000 km
English: 66,782,000 miles
Scientific Notation:
1.07476 x 108 km (0.718 A.U.)
By Comparison: 0.730 x
Earth
Aphelion (farthest)
Metric: 108,942,000 km
English: 67,693,000 miles
Scientific Notation:
1.08942 x 108 km (0.728 A.U.)
By Comparison: 0.716 x
Earth
Equatorial Radius
Metric: 6,051.8 km
English: 3,760.4 miles
Scientific Notation:
6.0518 x 103 km
By Comparison: 0.9488 x
Earth
Equatorial Circumference
Metric: 38,025 km
English: 23,627 miles
Scientific Notation:
3.8025 x 104 km
Volume
Metric: 928,400,000,000
km3
Scientific Notation:
9.284 x 1011 km3
By Comparison: 0.88 x
Earth's
Mass
Metric:
4,868,500,000,000,000,000,000,000 kg
Scientific Notation:
4.8685 x 1024 kg
By Comparison: 0.815 x
Earth
Density
Metric: 5.24 g/cm3
By Comparison: Comparable
to the average density of the Earth.
Surface Area
Metric: 460,200,000 km2
English: 177,700,000
square miles
Scientific Notation:
4.602 x 108 km2
By Comparison: 0.902 x
Earth
Equatorial Surface Gravity
Metric: 8.87 m/s2
English: 29.1 ft/s2
By Comparison: If you
weigh 100 pounds on Earth, you would weigh 91 pounds
on Venus.
Escape Velocity
Metric: 37,300 km/h
English: 23,200 mph
Scientific Notation:
1.036 x 104 m/s
By Comparison: 0.927 x
Earth
Sidereal Rotation Period (Length
of Day)
-243 Earth days (retrograde)
-5832 hours (retrograde)
By Comparison: 244 x
Earth
Sidereal Orbit Period (Length of
Year)
0.615 Earth years
224.7 Earth days
By Comparison: 0.615 x
Earth
Mean Orbit Velocity
Metric: 126,077 km/h
English: 78,341 mph
Scientific Notation:
35,021.4 m/s
By Comparison: 1.176 x
Earth
Orbital Eccentricity
.0068
By Comparison: 0.405 x
Earth
Orbital Inclination to Ecliptic
3.39 degrees
Equatorial Inclination to Orbit
177.3 degrees
By Comparison: 7.56 x
Earth
Orbital Circumference
Metric: 675,300,000 km
English: 419,600,000
miles
Scientific Notation:
6.753 x 108 km
By Comparison: 0.731 x
Earth
Minimum/Maximum Surface
Temperature
Metric: 462 °C
English: 864 °F
Scientific Notation: 735
K
Atmospheric Constituents
Carbon Dioxide, Nitrogen
Scientific Notation: CO2,
N2
By Comparison: Earth's
atmosphere consists mostly of N2 and O2.
CO2 is largely responsible for the
Greenhouse Effect and is used for carbonation in
beverages.
N2 is 80% of Earth's air and is a crucial
element in DNA.
Venus/Earth
Comparison
Bulk parameters
Venus Earth Ratio (Venus/Earth)
Mass (1024 kg) 4.8685 5.9736 0.815
Volume (1010 km3) 92.843 108.321 0.857
Equatorial radius (km) 6051.8 6378.1 0.949
Polar radius (km) 6051.8 6356.8 0.952
Volumetric mean radius (km) 6051.8 6371.0 0.950
Ellipticity (Flattening) 0.000 0.00335 0.0
Mean density (kg/m3) 5243 5515 0.951
Surface gravity (eq.) (m/s2) 8.87 9.80 0.905
Surface acceleration (eq.) (m/s2) 8.87 9.78 0.907
Escape velocity (km/s) 10.36 11.19 0.926
GM (x 106 km3/s2) 0.3249 0.3986 0.815
Bond albedo 0.750 0.306 2.45
Visual geometric albedo 0.65 0.367 1.77
Visual magnitude V(1,0) -4.40 -3.86 -
Solar irradiance (W/m2) 2613.9 1367.6 1.911
Black-body temperature (K) 231.7 254.3 0.911
Topographic range (km) 15 20 0.750
Moment of inertia (I/MR2) 0.33 0.3308 0.998
J2 (x 10-6) 4.458 1082.63 0.004
Number of natural satellites 0 1
Planetary ring system No No
Orbital parameters
Venus Earth Ratio (Venus/Earth)
Semimajor axis (106 km) 108.21 149.60 0.723
Sidereal orbit period (days) 224.701 365.256 0.615
Tropical orbit period (days) 224.695 365.242 0.615
Perihelion (106 km) 107.48 147.09 0.731
Aphelion (106 km) 108.94 152.10 0.716
Synodic period (days) 583.92 - -
Mean orbital velocity (km/s) 35.02 29.78 1.176
Max. orbital velocity (km/s) 35.26 30.29 1.164
Min. orbital velocity (km/s) 34.79 29.29 1.188
Orbit inclination (deg) 3.39 0.00 -
Orbit eccentricity 0.0067 0.0167 0.401
Sidereal rotation period (hrs) -5832.5 23.9345 243.686
Length of day (hrs) 2802.0 24.0000 116.750
Obliquity to orbit (deg) 177.36 23.45 (0.113)
Venus Observational Parameters
Discoverer: Unknown
Discovery Date: Prehistoric
Distance from Earth
Minimum (106 km) 38.2
Maximum (106 km) 261.0
Apparent diameter from Earth
Maximum (seconds of arc) 66.0
Minimum (seconds of arc) 9.7
Maximum visual magnitude -4.6
Mean values at inferior conjunction with Earth
Distance from Earth (106 km) 41.44
Apparent diameter (seconds of arc) 60.2
Venus Mean Orbital Elements
(J2000)
Semimajor axis (AU) 0.72333199
Orbital eccentricity 0.00677323
Orbital inclination (deg) 3.39471
Longitude of ascending node (deg) 76.68069
Longitude of perihelion (deg) 131.53298
Mean Longitude (deg) 181.97973
North Pole of Rotation
Right Ascension: 272.76
Declination : 67.16
Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0)
Venus Atmosphere
Surface pressure: 92 bars
Surface density: ~65. kg/m3
Scale height: 15.9 km
Total mass of atmosphere: ~4.8 x 1020 kg
Average temperature: 737 K (464 C)
Diurnal temperature range: ~0
Wind speeds: 0.3 to 1.0 m/s (surface)
Mean molecular weight: 43.45 g/mole
Atmospheric composition (near surface, by volume):
Major: 96.5% Carbon Dioxide (CO2), 3.5% Nitrogen (N2)
Minor (ppm): Sulfur Dioxide (SO2) - 150; Argon (Ar) - 70; Water (H2O) - 20;
Carbon Monoxide (CO) - 17; Helium (He) - 12; Neon (Ne) - 7
Data
compiled from The British Antarctic Study, NASA, Environment Canada,
UNEP, EPA and other sources as stated and credited Researched
by Charles Welch-Updated dailyThis Website is a project of the The
Ozone Hole Inc. a 501(c)(3) Nonprofit Organization
