Bulk Parameters

8/8/2019 Bulk Parameters

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Bulk parameters

Mass (1024 kg) 5.9736

Volume (1010 km3) 108.321

Equatorial radius (km) 6378.1

Polar radius (km) 6356.8

Volumetric mean radius (km) 6371.0Core radius (km) 3485

Ellipticity (Flattening) 0.00335

Mean density (kg/m3) 5515

Surface gravity (m/s2) 9.798

Surface acceleration (m/s2) 9.780

Escape velocity (km/s) 11.186

GM (x 106 km3/s2) 0.3986

Bond albedo 0.306

Visual geometric albedo 0.367

Visual magnitude V(1,0) -3.86

Solar irradiance (W/m2) 1367.6

Black-body temperature (K) 254.3

Topographic range (km) 20

Moment of inertia (I/MR2) 0.3308

J2 (x 10-6) 1082.63

Number of natural satellites 1

Planetary ring system No

Orbital parameters

Semimajor axis (106 km) 149.60

Sidereal orbit period (days) 365.256

Tropical orbit period (days) 365.242

Perihelion (106 km) 147.09

Aphelion (106 km) 152.10Mean orbital velocity (km/s) 29.78

Max. orbital velocity (km/s) 30.29

Min. orbital velocity (km/s) 29.29

Orbit inclination (deg) 0.000

Orbit eccentricity 0.0167

Sidereal rotation period (hrs) 23.9345

Length of day (hrs) 24.0000

Obliquity to orbit (deg) 23.44

Earth Mean Orbital Elements (J2000)

Semimajor axis (AU) 1.00000011

Orbital eccentricity 0.01671022

Orbital inclination (deg) 0.00005

Longitude of ascending node (deg) -11.26064

Longitude of perihelion (deg) 102.94719

Mean Longitude (deg) 100.46435


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North Pole ofRotation

Right Ascension: 0.00 - 0.641T

Declination : 90.00 - 0.557T

Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0)

T = Julian centuries from reference date

Terrestrial Magnetosphere

Dipole field strength: 0.3076 gauss-Re3

Latitude/Longitude of dipole N: 78.6 degrees N/70.1 degrees W

Dipole offset (planet center to dipole center) distance: 0.0725 Re

Latitude/Longitude of offset vector: 18.3 degrees N/147.8 degrees E

Note: Re denotes Earth radii, 6,378 km

Terrestrial Atmosphere

Surface pressure: 1014 mb

Surface density: 1.217 kg/m3

Scale height: 8.5 km

Total mass of atmosphere: 5.1 x 1018 kg

Total mass of hydrosphere: 1.4 x 1021 kg

Average temperature: 288 K (15 C)

Diurnal temperature range: 283 K to 293 K (10 to 20 C)

Wind speeds: 0 to 100 m/s

Mean molecular weight: 28.97 g/mole

Atmospheric composition (by volume, dry air):Major : 78.08% Nitrogen (N2), 20.95% Oxygen (O2),

Minor (ppm): Argon (Ar) - 9340; Carbon Dioxide (CO2) - 380

Neon (Ne) - 18.18; Helium (He) - 5.24; CH4 - 1.7

Krypton (Kr) - 1.14; Hydrogen (H2) - 0.55

Numbers do not add up to exactly 100% due to roundoff and uncertainty

Water is highly variable, typically makes up about 1%

The Moon

For information on the Moon, see the Moon

Fact Sheet

Notes on the factsheets - definitions of parameters, units, notes on sub- and

superscripts, etc.


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Planetary Fact Table - metric unitsPlanetary Fact Table - U.S. units

Planetary Fact Table - Earth ratio

Earth PageDirectory to o

Discovered By Known by the Ancients

Date of Discovery Unknown

Average Distance from the Sun Metric: 149,597,890 km

English: 92,955,820 miles

Scientific Notation: 1.4959789 x 108km (1.000 A.U.)

Perihelion (closest) Metric: 147,100,000 km



Aphelion (farthest) Metric: 152,100,000 km



Equatorial Radius Metric: 6,378.14 km

English: 3,963.19 miles

Scientific Notation: 6.37814 x 103 km

By Comparison: 1 x Earth's

Equatorial Circumference Metric: 40,075 km

English: 24,901 miles

Scientific Notation: 4.0075 x 104 km

Volume Metric: 1,083,200,000,000 km3

English: 259,900,000,000 mi3

Scientific Notation: 1.0832 x 1012km3

By Comparison: 1 x Earth's

Mass Metric: 5,973,700,000,000,000,000,000,000 kg

Scientific Notation: 5.9737 x 1024 kg

Density Metric: 5.515 g/cm3

Surface Area Metric: 510,065,700 km2

English: 196,937,500 square miles

Scientific Notation: 5.100657 x 108km2

Equatorial Surface Gravity Metric: 9.766 m/s2

English: 32.041 ft/s2

Escape Velocity Metric: 40,248 km/h

English: 25,009 mph

Scientific Notation: 11,180 m/s


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Sidereal Rotation Period (Length of Day) 0.99726968 Earth days

23.934 hours

Sidereal Orbit Period (Length of Year) 1.0000174 Earth years

365.24 Earth days

Mean Orbit Velocity Metric: 107,229 km/h

English: 66,629 mph

Scientific Notation: 29,785.9 m/s

Orbital Eccentricity 0.01671022

Orbital Inclination to Ecliptic 0.00005 degrees

Equatorial Inclination to Orbit 23.45 degrees

Orbital Circumference Metric: 924,375,700 km


Scientific Notation: 9.243757 x 108km

Minimum/Maximum Surface Temperature Metric: -88/58 (min/max) C

English: -126/136 (min/max) FScientific Notation: 185/331 (min/max) K

Atmospheric Constituents Nitrogen, Oxygen

Scientific Notation: N2, O2

By Comparison: N2is 80% of Earth's air and is a crucial element in DNA

ther Planetary Fact Sheets

Planetary Symbol: Surface Gravity: 9.78 m/s^2

Diameter:12,753 km (7,926miles)

Rotation Period with respect to

Sun (Length ofDay):24 hrs

Mass:

5.98x10^24

kilograms(6.5e21 tons)

Rotation Period with respect to

stars (Sidereal Day):

23 hrs 56

min

Density: 5,515 kg/m^3Revolution Period about the Sun

(Length ofa Year):

365 days 5

hrs

Minimum Distance

from Sun:

146 million km(91 million miles)

Tilt ofAxis: 23o 27"

Maximum Distance

from Sun:

152 million km(94.5 million miles)

Temperature:

-89o

C to57.7oC(-128

oF to

136oF)

Orbital Semimajor

Axis:1.0 AU Average Surface Temperature (K): 287K

Satellites: 1 (the Moon)


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Sun Reference Data

Diameter:1.4 million km

(870,000 miles)Age: 4.5 billion years

Mass: 330,000 x Earth Distance from Earth:149.6 million km (93

million miles)

Density: 1.41 (water=1)Distance to Nearest

Star:4.3 light years

Solar Wind Speed: 3 million km/hr. Luminosity:390 billion billion

megawatts

Solar Cycle: 8 - 11 yearsTemperature at

surface:5,500

oC (9,932

oF)

Temperature at

Core:

14 milliono

C (22.5

milliono

F)

Temperature of

Sunspots:4,000

oC (7,232

oF)

Rotation Period at

Equator:25 Earth days

Rotation Period at

Poles:35 Earth days

The North Star, also called the Pole Star or Polaris, is the star that theearth's axis points toward in the Northern sky. For many years, people have

been fascinated with this star and the fact that it doesn't seem to move inthe sky. Some have created legends explaining why the star stands still. As

more detailed scientific instrumentation has become available, scientistshave begun to study more about Polaris. Surprisingly, it is a rich subject

consisting of a binary star system.

Why Do We Care about the North Star?

For many years, the North Star has been used as a navigation aid and to

chart navigational maps. It has also been used to measure astronomicallatitude since we map latitudes to the equivalent sky positions: the North

Pole equates to +90 degrees latitude on Earth as does its projection into thesky. In addition to these functional uses, over time many cultures have built

folklore around the North Star. Even people with little interest in astronomyor mapmaking know about the North Star, and some have created stories

explaining why it seemingly never moves.

The most famous story about the North Star is the Native American mythexplaining why the North Star stands still. In this story, a brave son Na-Gah


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tried to impress his father by climbing the tallest cliff he could find. Through

difficult conditions he persisted until he found himself at the top of a very

high mountain. The mountain was so tall that Na-Gah looked down on all theother mountains. Unfortunately, there was no way down. When his father

came looking for him, he found Na-Gah stuck high above. Not wanting his

son to suffer for his bravery, he turned Na-Gah into a star that can be seenand honored by all living things.

Polaris: The Current North Star

Today the Earth's axis points within one degree of Polaris, the brightest star

in the constellation Ursa Minor (also called the Little Bear or the LittleDipper). Polaris appears to be in a fixed position in the sky throughout the

year. All other stars and constellations seem to revolve around the North

Star.

To find Polaris in the sky, locate the Big Dipper and follow the two stars atthe end of the basin upward. This should lead you directly to Polaris. It is the

last star in the tail of the Little Dipper.

Why isn't the North Star Fixed?

Over the course of time, the North Star changes. Right now Polaris is withinone degree of true north, but at other times the North Star has been and will

again be Thuban (the brightest star in the constellation Draco), Vega (the

brightest star in the constellation Lyra), and Alpha Cephei (the brightest star

in the constellation Cepheus).

The North Star changes over time because the direction of the earth's axischanges slowly over time. Since by definition the North Star is the star mostclosely aligned with the earth's axis, as the axis moves the nearest star

changes too.

This type of axis movement is similar to that of a spinning top. As the top

slows, the axis of rotation changes as the top draws out each rotation; that

is to say that the stem of the top itself traces out a circular pattern rather

than pointing at a single spot or staying mostly still. If you draw an

imaginary line of the earth's axis and continue it up to the sky, it will make asimilar path. This type of axis rotation is called precession.

In the case of the earth, precession is caused by the gravitational pull of the

sun and the moon. The earth's axis makes one complete rotation over the

course of approximately 26,000 years. If you trace the path of the axis inthe sky, you will find that Polaris, Vega, Thuban, and Alpha Cephei all fall on


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or very close to it. So when the earth's axis is at a point on the path near

Vega, Vega becomes the North Star while Thuban is the North Star when the

axis is near it on the path.

Five thousand years ago, Thuban was the North Star. Five thousand years

from now, the North Star will be Alpha Cephei. Seven thousand years afterthat, it will be Vega. Nine thousand years after that, Thuban will be the

North Star again. At these dates, the various stars will be at the closest to

absolute north. For some time before, the relevant star will be approachingdue north and it will be receding for some time after the time listed. In these

interim times, the North Star is whichever star is closest to north.

A pole staris a visible star, especially a prominent one, that is approximately aligned with theEarth'saxis

of rotation; that is, a star whose apparent position is close to one of thecelestial poles, and which lies

approximately directly overhead when viewed from the Earth'sNorth Pole orSouth Pole. (A similar

concept also applies to other planets.)

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