Micro / Macro numbers in Science

Jai Ganesh · 2015-10-25 17:30:43

The colors of the visible light spectrum : color wavelength interval : frequency interval
red ~ 700–635 nm ~ 430–480 THz
orange ~ 635–590 nm ~ 480–510 THz
yellow ~ 590–560 nm ~ 510–540 THz
green ~ 560–520 nm ~ 540–580 THz
cyan ~ 520–490 nm ~ 580–610 THz
blue ~ 490–450 nm ~ 610–670 THz
violet ~ 450–400 nm ~ 670–750 THz

Jai Ganesh · 2015-10-25 18:03:39

Color, wavelength, frequency and energy of light

(nm) (THz) eV
Infrared : >1000 : <300 : <1.00 : <1.24 : <120
Red    : 700 : 428    : 1.43 : 1.77 : 171
Orange : 620 : 484 : 1.61    : 2.00 : 193
Yellow : 580    :517 : 1.72    : 2.14 : 206
Green : 530    : 566    : 1.89    : 2.34 : 226
Blue    : 470    : 638    : 2.13    : 2.64 : 254
Violet : 420    : 714    : 2.38    :2.95    : 285
Near
ultraviolet : 300    : 1000    : 3.33    :4.15    : 400
Far
ultraviolet : <200    : >1500    : >5.00    : >6.20    : >598

Last edited by Jai Ganesh (2015-10-28 14:04:20)

Jai Ganesh · 2015-10-26 00:17:26

Planets: Orbital Properties
Planet : distance : revolution : eccentricity : inclination

Mercury : 0.387 : 87.969 d : 0.2056 : 7.005
Venus : 0.723 : 224.701 d : 0.0068 : 3.3947
Earth : 1.000 : 365.256 d : 0.0167 : 0.0000
Mars : 1.524 : 686.98 d : 0.0934 : 1.851
Jupiter : 5.203 : 11.862 y : 0.0484 : 1.305
Saturn : 9.537 : 29.457 y : 0.0542 : 2.484
Uranus : 19.191 : 84.011 y : 0.0472 :0.770
Neptune : 30.069 : 164.79 y : 0.0086 : 1.769
Pluto : 39.482 : 247.68 y : 0.2488 : 17.142
Notes: Distance is the semi-major axis in astronomical units (1 A.U. =

km); rotation and revolution are the sidereal rotation period and sidereal orbital period, h = hours, d = Earth sidereal days; eccentricity is the orbital eccentricity = 1 – (perihelion/semi-major axis); and inclination is the tilt of the orbit with respect to the Earth's orbit. The planet's "mean orbital elements (J2000)" are used for the inclination, eccentricity, and distance. [Yes, Pluto is a dwarf planet.]
Planets: Physical Characteristics
Planet : Mass : Diameter : density : oblateness : rotation axis tilt mag. field

   : (× ME) : (km) : (g/cm3) : [=(De – Dp)/De] : (deg) : (× Earth's)
Mercury : 0.0553 : 4879 : 5.427 : 0.000 : 58.785 d : ~0    : 0.0006
Venus : 0.815 : 12,104 : 5.243 : 0.000 : 243.686 d : 177.36 : 0.00
Earth : 1.000 : 12,742 : 5.515 : 0.00335 : 23.9345 h : 23.45 : 1.000
Mars : 0.107 : 6779 : 3.933 : 0.00648 : 24.6229 h : 25.19 : 0.00
Jupiter : 317.83 : 139,822 : 1.326 : 0.06487 : 9.9250 h : 3.13 : 19,519
Saturn : 95.159 : 116,464 : 0.687 : 0.09796 : 10.656 h : 26.73 : 578
Uranus : 14.536 : 50,724 : 1.270 : 0.02293 : 17.24 h    : 97.77 : 47.9
Neptune : 17.147 : 49,244 : 1.638 : 0.01708 : 16.11 h    :28.32 :27.0
Pluto : 0.0021 : 2390 : 1.750 : 0.000 : 6.405 d    :122.53 : 0.00

Last edited by Jai Ganesh (2015-10-26 15:59:49)

Jai Ganesh · 2015-10-26 05:56:36

Another key limitation is the sensitivity of the instrument used to make the measurement. In general, as computers have advanced and telescope mirror technology has improved over the years, measurements that are made in recent years have more weight among scientists than those that are made long ago.

Paradoxically, the brightest stars are among the least studied by astronomers, but there is at least one recent effort to catalog their luminosity. A constellation of satellites called BRITE (BRight Target Explorer) will measure the variability of brightness between stars. Participants in the six-satellite project include Austria, Canada and Poland. The first two satellites launched successfully in 2013.
Top 26 brightest stars, as seen from Earth
Common
name = Constellation = App. Mag. *variable = Absolute Magnitude = Distance from Earth
Sun : n/a : -26.72 : 4.2 : 93 million miles
Sirius : Canis Major : -1.46 : 1.4 : 8.6 light-years
Canopus : Carina : -0.72 : -2.5 : 74 ly
Rigil Kentaurus : (Alpha Centauri) Centaurus : -0.27 : 4.4 : 4.3 ly
Arcturus : Boötes : -0.04 : 0.2 : 34 ly
Vega : Lyra : 0.03 : 0.6 : 25 ly
Capella : Auriga : 0.08 : 0.4 : 41 ly
Rigel : Orion : 0.12 : -8.1 : 1,400 ly
Procyon : Canis Minor : 0.38 : 2.6 : 11.4 ly
Achernar : Eridanus : 0.46 : -1.3 : 69 ly
Betelgeuse : Orion : 0.50* : -7.2 : 1,400 ly
Hadar : Centaurus : 0.61* : -4.4 : 320 ly
Acrux : Crux : 0.76 : -4.6: 510 ly
Altair : Aquila : 0.77 : 2.3 : 16 ly
Aldebaran : Taurus : 0.85* : -0.3 : 60 ly
Antares : Scorpius : 0.96* : -5.2 : 520 ly
Spica : Virgo : 0.98* : -3.2 : 220 ly
Pollux : Gemini : 1.14 : 0.7 : 40 ly
Fomalhaut : Piscis Austrinis : 1.16 : 2.0 : 22 ly
Becrux (Beta Crucis) : Crux : 1.25* : -4.7 : 460 ly
Deneb : Cygnus : 1.25 : -7.2 : 1,500 ly
Regulus : Leo : 1.35 : -0.3 : 69 ly
Adhara : Canis Major : 1.50 : -4.8 : 570 ly
Castor : Gemini : 1.57 : 0.5 : 49 ly
Gacrux (Gamma Crucis) : Crux : 1.63* : -1.2 : 120 ly
Shaula : Scorpius : 1.63* :-1.2 : 330 ly
(Source: Chris Dolan, University of Wisconsin-Madison Department of Astronomy. He adapted it from Norton's 2000.0, 18th edition (1989) along with Bill Baity's Sky Pages.)

Last edited by Jai Ganesh (2015-10-26 15:32:38)

Jai Ganesh · 2015-10-26 06:47:12

The Galactic Center is the rotational center of the Milky Way. The estimations for its location range from 7.6 to 8.7 kiloparsecs (about 25 000 to 28 000 lightyears), in the direction of the constellations Sagittarius, Ophiuchus, and Scorpius where the Milky Way appears brightest. There is strong evidence consistent with the existence of a supermassive black hole at the Galactic Center of the Milky Way.

Distance to the Galactic Center

The exact distance between the Solar System and the Galactic Center is not certain. The latest estimates from geometric-based methods and standard candles yield the following distances to the Galactic Center:

or

.

An accurate determination of the distance to the Galactic Center as established from variable stars (e.g. RR Lyrae variables) or standard candles (e.g. red-clump stars) is hindered by countless effects, which include: an ambiguous reddening law; a bias for smaller values of the distance to the Galactic Center because of a preferential sampling of stars toward the near side of the Galactic bulge owing to interstellar extinction; and an uncertainty in characterizing how a mean distance to a group of variable stars found in the direction of the Galactic bulge relates to the distance to the Galactic Center.

The nature of the Milky Way's bar, which extends across the Galactic Center, is also actively debated, with estimates for its half-length and orientation spanning between 1-5 kpc (short or a long bar) and 10-50°. Certain authors advocate that the Milky Way features two distinct bars, one nestled within the other] The bar elineated by red-clump stars (see also red giant), however, RR Lyr variables do not trace a prominent Galactic bar. The bar may be surrounded by a ring called the "5-kpc ring" that contains a large fraction of the molecular hydrogen present in the Milky Way, as well as most of the Milky Way's star formation activity. Viewed from the Andromeda Galaxy, it would be the brightest feature of the Milky Way.

Last edited by Jai Ganesh (2015-11-03 17:06:31)

Jai Ganesh · 2015-10-26 14:20:53

Pressure varies smoothly from the Earth's surface to the top of the mesosphere. Although the pressure changes with the weather, NASA has averaged the conditions for all parts of the earth year-round. As altitude increases, atmospheric pressure decreases. One can calculate the atmospheric pressure at a given altitude. Temperature and humidity also affect the atmospheric pressure, and it is necessary to know these to compute an accurate figure. The graph at right was developed for a temperature of 15 °C and a relative humidity of 0%.

At low altitudes above the sea level, the pressure decreases by about 1.2 kPa for every 100 meters. For higher altitudes within the troposphere, the following equation (the barometric formula) relates atmospheric pressure p to altitude h

,

where the constant parameters are as described below:
Parameter : Description : Value

: sea level standard atmospheric pressure : 101325 Pa
L temperature lapse rate, = for dry air
= constant pressure specific heat
= sea level standard temperature = 288.15 K
g = Earth-surface gravitational acceleration
M = molar mass of dry air
R = universal gas constant .

Last edited by Jai Ganesh (2015-10-26 15:01:47)

Jai Ganesh · 2015-10-27 16:42:06

Moon :

Orbital characteristics : Perigee 362600 km
(356400–370400 km)
Apogee 405400 km (404000–406700 km)
Semi-major axis : 384399 km (0.00257 AU)
Eccentricity : 0.0549
Orbital period : 27.321582 d
(27 d 7 h 43.1 min)
Synodic period : 29.530589 d
(29 d 12 h 44 min 2.9 s)
Average orbital speed : 1.022 km/s
Inclination : 5.145° to the ecliptic
Longitude of ascending node
regressing by one revolution in 18.6 years
Argument of perigee :
progressing by one revolution in 8.85 years
Satellite of : Earth
Physical characteristics
Mean radius : 1737.10 km (0.273 Earths)
Equatorial radius : 1738.14 km (0.273 Earths)
Polar radius : 1735.97 km (0.273 Earths)
Flattening : 0.00125
Circumference : 10921 km (equatorial)
Surface area :

square kilometers : (0.074 Earths)
Volume : cubic kilometers (0.020 Earths)
Mass : kg (0.012300 Earths)
Mean density :
0.606 × Earth
Surface gravity : (0.1654 g)
Moment of inertia factor :
Escape velocity : 2.38 km/s
Sidereal rotation period : 27.321582 d (synchronous)
Equatorial rotation velocity : 4.627 m/s
Axial tilt :
1.5424° to ecliptic
6.687° to orbit plane

Albedo : 0.136
Surface temp. : min : mean : max
Equator : 100 K : 220 K : 390 K
85°N : 70 K : : 130 K : 230 K
Apparent magnitude : -2.5 to -12.9 : -12.74 (mean full moon)
Angular diameter : 29.3 to 34.1 arcminutes
Atmosphere :
Surface pressure :

(day) : (night)

Composition by volume : He - Ar - Ne - Na - K - H - Rn

Jai Ganesh · 2015-10-28 07:00:47

List of SI prefixes

The BIPM specifies twenty prefixes for the International System of Units (SI).

SI prefixes

Name : Symbol :Short scale : Long scale
yotta : Y :

: : 1000000000000000000000000 : septillion :    quadrillion : 1991
zetta : Z :    : : 1000000000000000000000 : sextillion :    thousand trillion or trilliard : 1991
exa : E :    : : 1000000000000000000 : quintillion :    trillion : 1975
peta : P : :    : 1000000000000000 : quadrillion : thousand billion or billiard : 1975
tera : T :    : : : 1000000000000 : trillion :    billion : 1960
giga :: G : : : 1000000000 : billion : thousand million or milliard : 1960
mega : M : : :1000000 : million : 1960 (1873)
kilo : k :    : : 1000 : thousand : 1960 (1795)
hecto : h :    : : 100 : hundred : 1960 (1795)
deca : da :    : : 10 : ten : 1960 (1795)
1 :    one
deci : d :    : : 0.1 :    tenth : 1960 (1795)
centi : c :    : : 0.01 : hundredth : 1960 (1795)
milli : m    : : : 0.001 : thousandth : 1960 (1795)
micro : : :    : 0.000001 :    : millionth : 1960 (1873)
nano : n :    0.000000001 : billionth :    thousand millionth 1960
pico : p :    : : 0.000000000001 : trillionth : billionth 1960[
femto : f :    : : 0.000000000000001 :    quadrillionth :    thousand billionth 1964
atto : a : : : 0.000000000000000001 :    quintillionth :    trillionth : 1964
zepto : z :    :    : 0.000000000000000000001 :    sextillionth    : thousand trillionth : 1991
yocto : y : : :    0.000000000000000000000001    : septillionth :    quadrillionth :    1991

The metric system was introduced in 1795 with several metric prefixes, of which, however, only six were adopted as SI prefixes by the 11th CGPM conference in 1960, whereas myria

as well as double and demi were not adopted. In 1873, micro and mega were recommended by the British Association for the Advancement of Science. The other dates relate to recognition by a resolution of the CGPM.
Each prefix name has a symbol which is used in combination with the symbols for units of measure. For example, the symbol for kilo- is k, and is used to produce km, kg, and kW, which are kilometre, kilogram, and kilowatt, respectively.

Prefixes may not be used in combination. This also applies to mass, for which the SI base unit (kilogram) already contains a prefix. For example, milligram (mg) is used instead of microkilogram (µkg).

Last edited by Jai Ganesh (2015-11-03 17:15:12)

Jai Ganesh · 2015-10-28 14:01:50

The Mohs scale of mineral hardness is a qualitative ordinal scale that characterizes the scratch resistance of various minerals through the ability of a harder material to scratch a softer material. It was created in 1812 by the German geologist and mineralogist Friedrich Mohs and is one of several definitions of hardness in materials science, some of which are more quantitative.
As the hardest known naturally occurring substance when the scale was designed, diamonds are at the top of the scale. The hardness of a material is measured against the scale by finding the hardest material that the given material can scratch, and/or the softest material that can scratch the given material. For example, if some material is scratched by apatite but not by fluorite, its hardness on the Mohs scale would fall between 4 and 5. "Scratching" a material for the purposes of the Mohs scale means creating non-elastic dislocations visible to the naked eye. Frequently, materials that are lower on the Mohs scale can create microscopic, non-elastic dislocations on materials that have a higher Mohs number. While these microscopic dislocations are permanent and sometimes detrimental to the harder material's structural integrity, they are not considered "scratches" for the determination of a Mohs scale number.

The Mohs scale is a purely ordinal scale. For example, corundum (9) is twice as hard as topaz (8), but diamond (10) is four times as hard as corundum. The table below shows the comparison with the absolute hardness measured by a sclerometer, with pictorial examples.

Mohs hardness : Mineral : Absolute hardness
1    : Talc : 1
2    : Gypsum : 3
3    : Calcite : 9
4    : Fluorite : 21
5    : Apatite : 48
6    : Orthoclase feldspar : 72
7    : Quartz    : 100
8    : Topaz    : 200
9    : Corundum : 400
10    : Diamond : 1600

Jai Ganesh · 2015-10-28 14:56:01

Melting point is the temperature at which a substance changes from solid to liquid state.

Melting points for some metals and alloys are indicated below.
Metal : Melting Point
Degrees C: : Degrees F
Admiralty Brass : 900 - 940 : 1650 - 1720
Aluminum    : 660 : 1220
Aluminum Alloy : 463 - 671 : 865 - 1240
Aluminum Bronze : 1027 - 1038 : 1881 - 1900
Antimony    : 630 : 1170
Babbitt    : 249 : 480
Beryllium    : 1285 : 2345
Beryllium Copper : 865 - 955 : 1587 - 1750
Bismuth    :271.4 : 520.5
Brass, Red    : 1000 : 1832
Brass, Yellow    : 930 : 1710
Cadmium    : 321 : 610
Chromium    : 1860 : 3380
Cobalt    : 1495 : 2723
Copper    : 1084 : 1983
Cupronickel : 1170 - 1240 : 2140 - 2260
Gold, 24K Pure : 1063 : 1945
Hastelloy C : 1320 - 1350 : 2410 - 2460
Inconel    : 1390 - 1425 : 2540 - 2600
Incoloy    : 1390 - 1425 : 2540 - 2600
Iridium    : 2450 : 4440
Iron, Wrought : 1482 - 1593 : 2700 - 2900
Iron, Gray Cast : 1127 - 1204 : 2060 - 2200
Iron, Ductile : 1149    : 2100
Lead    : 327.5    : 621
Magnesium : 650    : 1200
Magnesium Alloy : 349 - 649 : 660 - 1200
Manganese : 1244 : 2271
Manganese bronze : 865 - 890 : 1590 - 1630
Mercury    : -38.86 : -37.95
Molybdenum : 2620 : 4750
Monel    : 1300 - 1350 : 2370 - 2460
Nickel    : 1453 : 2647
Niobium (Columbium) : 2470 : 4473
Osmium : 3025 : 5477
Palladium    : 1555 : 2831
Phosphorus : 44 :111
Platinum    : 1770 : 3220
Plutonium    : 640 : 1180
Potassium    : 63.3 : 146
Red Brass    : 990 - 1025 : 1810 - 1880
Rhenium    :3186 : 5767
Rhodium    :1965 : 3569
Ruthenium : 2482 : 4500
Selenium    : 217 : 423
Silicon    : 1411 :2572
Silver, Coin : 879 : 1615
Silver, Pure : 961 : 1761
Silver, Sterling : 893 : 1640
Sodium    :97.83 : 208
Steel, Carbon : 1425 - 1540 : 2600 - 2800
Steel, Stainless : 1510 : 2750
Tantalum    : 2980 : 5400
Thorium    : 1750 : 3180
Tin    : 232 : 449.4
Titanium    : 1670 : 3040
Tungsten    : 3400 : 6150
Uranium    : 1132 : 2070
Vanadium    :1900 : 3450
Yellow Brass : 905 - 932 : 1660 - 1710
Zinc    : 419.5 : 787
Zirconium    : 1854 : 3369

Jai Ganesh · 2015-10-29 08:33:20

Surface Gravity of the Planets and the Sun

Rank : Name : Surface Gravity (meter pr. square second)
1    :Sun    : 274
2    : Jupiter : 24.92
3    : Neptune : 11.15
4    : Saturn : 10.44
5    : Earth : 9.798
6    : Uranus : 8.87
7    : Venus : 8.87
8    : Mars    : 3.71
9    : Mercury : 3.7
10    : Moon : 1.62
11    : Pluto : 0.58

Jai Ganesh · 2015-10-29 12:13:28

Planets data :'
   Mercury : Venus : Earth : Mars : Jupiter : Saturn : Uranus : Neptune
diameter (Earth=1) : 0.382 : 0.949 : 1    : 0.532 : 11.209 : 9.44 : 4.007 : 3.883
diameter (km)    : 4,878 : 12,104 : 12,756 : 6,787 : 142,800 : 120,000 : 51,118 : 49,528
mass (Earth=1) : 0.055 : 0.815 : 1    : 0.107 : 318 : 95    : 15    : 17
mean distance from Sun (AU) : 0.39 : 0.72 : 1    :1.52 : 5.20 : 9.54 : 19.18 : 30.06
orbital period (Earth years) : 0.24 : 0.62 : 1    : 1.88 : 11.86 : 29.46 : 84.01 : 164.8
orbital eccentricity : 0.2056 : 0.0068    : 0.0167 : 0.0934 : 0.0483 : 0.0560 : 0.0461 : 0.0097
mean orbital velocity (km/sec): 47.89 : 35.03: 29.79 : 24.13 : 13.06 : 9.64 : 6.81 : 5.43
rotation period (in Earth days) : 58.65 :-243*: 1    : 1.03 : 0.41 : 0.44 : -0.72*    : 0.72
inclination of axis (degrees) : 0.0 :177.4 : 23.45 : 23.98 : 3.08 : 26.73 : 97.92    : 28.8
mean temperature at surface (C): -180 to 430 : 465 : -89 to 58 : -82 to 0 :-150 : -170 : -200 : -210
gravity at equator (Earth=1) :0.38 : 0.9 : 1 : 0.38 :2.64    : 0.93    : 0.89 : 1.12
escape velocity (km/sec) :4.25 :10.36    : 11.18 : 5.02 : 59.54    : 35.49    :21.29 : 23.71
mean density (water=1) : 5.43 : 5.25    :5.52 : 3.93 : 1.33    :0.71    : 1.24 : 1.67
atmospheric composition :none :CO2 :N2 + O2 :CO2 : H2+He    : H2+He    : H2+He : H2+He
number of moons : 0 : 0    :1    : 2    : 63       : 62    : 27    : 13
rings? : no    : no : no    : no    : yes    : yes    : yes    : yes

Jai Ganesh · 2015-10-30 16:51:54

Atomic Radii

Jai Ganesh · 2015-10-31 17:17:03

Subatomic particle

Classification

By statistics

The Standard Model classification of particles

Any subatomic particle, like any particle in the 3-dimensional space that obeys laws of quantum mechanics, can be either a boson (an integer spin) or a fermion (a half-integer spin).

By composition

The elementary particles of the Standard Model include:

(i) Six "flavors" of quarks: up, down, bottom, top, strange, and charm;

(ii) Six types of leptons: electron, electron neutrino, muon, muon neutrino, tau, tau neutrino;

(iii) Twelve gauge bosons (force carriers): the photon of electromagnetism, the three W and Z bosons of the weak force, and the eight gluons of the strong force;

(iv) The Higgs boson.

Various extensions of the Standard Model predict the existence of an elementary graviton particle and many other elementary particles.

Composite subatomic particles (such as protons or atomic nuclei) are bound states of two or more elementary particles.
For example, a proton is made of two up quarks and one down quark, while the atomic nucleus of helium-4 is composed of two protons and two neutrons. The neutron is made of two down quarks and one up quark. Composite particles include all hadrons: these include baryons (such as protons and neutrons) and mesons (such as pions and kaons).

By mass

In special relativity, the energy of a particle at rest equals its mass times the speed of light squared

. That is, mass can be expressed in terms of energy and vice versa. If a particle has a frame of reference where it lies at rest, then it has a positive rest mass and is referred to as massive.

All composite particles are massive. Baryons (meaning "heavy") tend to have greater mass than mesons (meaning "intermediate"), which in turn tend to be heavier than leptons (meaning "lightweight"), but the heaviest lepton (the tau particle) is heavier than the two lightest flavours of baryons (nucleons). It is also certain that any particle with an electric charge is massive.

All massless particles (particles whose invariant mass is zero) are elementary. These include the photon and gluon, although the latter cannot be isolated.

Jai Ganesh · 2015-11-03 09:22:22

Moon : Orbital characteristics
Perigee : 362600 km (356400–370400 km)
Apogee : 405400 km (404000–406700 km)
Semi-major axis : 384399 km (0.00257 AU)
Eccentricity ; 0.0549
Orbital period : 27.321582 d (27 d 7 h 43.1 min)
Synodic period : 29.530589 d (29 d 12 h 44 min 2.9 s)
Average orbital speed : 1.022 km/s
Inclination : 5.145° to the ecliptic
Longitude of ascending node : regressing by one revolution in 18.6 years
Argument of perigee : progressing by one revolution in 8.85 years
Satellite of : Earth

Physical characteristics
Mean radius : 1737.10 km (0.273 Earths)
Equatorial radius : 1738.14 km (0.273 Earths)
Polar radius : 1735.97 km (0.273 Earths)
Flattening : 0.00125
Circumference : 10921 km (equatorial)
Surface area :

square kilometers. (0.074 Earths)
Volume : cubic kilometers. (0.020 Earths)
Mass : kilograms (0.012300 Earths)
Mean density : 3.3464 g/cubic centimeters : 0.606 × Earth
Surface gravity : 1.622 m/s^2 (0.1654 g)
Moment of inertia factor :
Escape velocity : 2.38 km/s
Sidereal rotation period : 27.321582 d (synchronous)
Equatorial rotation velocity : 4.627 m/s
Axial tilt : 1.5424° to ecliptic : 6.687° to orbit plane
Albedo : 0.136
Surface temp. : min : mean : max
Equator    : 100 K : 220 K : 390 K
85°N    : 70 K : 130 K : 230 K
Apparent magnitude : -2.5 to -12.9 : -12.74 (mean full moon)
Angular diameter :    : 29.3 to 34.1 arcminutes

Atmosphere
Surface pressure :

(day) : (night)

Composition by volume : He - Ar - Ne - Na - K - H - Rn

Last edited by Jai Ganesh (2015-11-03 09:34:00)

Jai Ganesh · 2015-11-07 10:39:37

This is a list of the chemical elements according to increasing density (g/cm3) measured at standard temperature and pressure (100.00 kPa and 0°C). As you would expect, the first elements in the list are gases.

Hydrogen - 0.00008988
Helium - 0.0001785
Neon - 0.0008999
Nitrogen - 0.0012506
Oxygen - 0.001429
Fluorine - 0.001696
Argon - 0.0017837
Chlorine - 0.003214
Krypton - 0.003733
Xenon - 0.005887
Radon - 0.00973
Lithium - 0.534
Potassium - 0.862
Sodium - 0.971
Rubidium - 1.532
Calcium - 1.54
Magnesium - 1.738
Phosphorus - 1.82
Beryllium - 1.85
Francium - 1.87
Caesium - 1.873
Sulfur - 2.067
Carbon - 2.267
Silicon - 2.3296
Boron - 2.34
Strontium - 2.64
Aluminium - 2.698
Scandium - 2.989
Bromine - 3.122
Barium - 3.594
Yttrium - 4.469
Titanium - 4.540
Selenium - 4.809
Iodine - 4.93
Europium - 5.243
Germanium - 5.323
Radium - 5.50
math - 5.776
Gallium - 5.907
Vanadium - 6.11
Lanthanum - 6.145
Tellurium - 6.232
Zirconium - 6.506
Antimony - 6.685
Cerium - 6.770
Praseodymium - 6.773
Ytterbium - 6.965
Astatine ~7
Neodymium - 7.007
Zinc - 7.134
Chromium - 7.15
Promethium - 7.26
Tin - 7.287
Indium - 7.310
Manganese - 7.44
Samarium - 7.52
Iron - 7.874
Gadolinium - 7.895
Terbium - 8.229
Dysprosium - 8.55
Niobium - 8.570
Cadmium - 8.69
Holmium - 8.795
Cobalt - 8.86
Nickel - 8.912
Copper - 8.933
Erbium - 9.066
Polonium - 9.32
Ununhexium >9.32
Thulium - 9.321
Bismuth - 9.807
Ununpentium >9.807
Lutetium - 9.84
Lawrencium >9.84
Actinium - 10.07
Molybdenum - 10.22
Silver - 10.501
Lead - 11.342
Ununquadium >11.342
Technetium - 11.50
Thorium - 11.72
Thallium - 11.85
Ununtrium >11.85
Palladium - 12.020
Ruthenium - 12.37
Rhodium - 12.41
Hafnium - 13.31
Einsteinium - 13.5 (Estimate)
Curium - 13.51
Mercury - 13.5336
Ununbium >13.5336
Americium - 13.69
Berkelium - 14.79
Californium - 15.10
Protactinium - 15.37
Tantalum - 16.654
Rutherfordium - 18.1
Uranium - 18.95
Tungsten - 19.25
Gold - 19.282
Roentgenium >19.282
Plutonium - 19.84
Neptunium - 20.25
Rhenium - 21.02
Platinum - 21.46
Darmstadtium >21.46
Osmium - 22.610
Iridium - 22.650

Jai Ganesh · 2015-11-11 12:26:57

In chemistry and physics, the Avogadro constant (symbols: L,

) is the number of constituent particles, usually atoms or molecules, that are contained in the amount of substance given by one mole. Thus it is the proportionality factor that relates the molar mass of a compound to its mass. Avogadro's constant has the value in the International System of Units (SI).

Previous definitions of chemical quantity involved Avogadro's number, a historical term closely related to the Avogadro constant but defined differently: Avogadro's number was initially defined by Jean Baptiste Perrin as the number of atoms in one gram-molecule of atomic hydrogen, meaning one gram of hydrogen. This number is also known as Loschmidt constant in German texts. The constant was later redefined as the number of atoms in 12 grams of the isotope carbon-12 (

) and still later generalized to relate amounts of a substance to their molecular weight. For instance, to a first approximation, 1 gram of hydrogen element (H), having the atomic (mass) number 1, has hydrogen atoms. Similarly, 12 grams of , with the mass number of 12 (atomic number 6), has the same number of carbon atoms, . Avogadro's number is a dimensionless quantity and has the numerical value of the Avogadro constant given in base units. In contrast, the Avogadro constant has the dimension of reciprocal amount of substance.

Revisions in the base set of SI units necessitated redefinitions of the concepts of chemical quantity and so Avogadro's number, and its definition, was deprecated in favor of the Avogadro constant and its definition. Changes in the SI units are proposed that will precisely fix the value of the constant to exactly

when it is expressed in the unit (see New SI definitions, in which an "X" at the end of a number means one or more final digits yet to be agreed upon).

Last edited by Jai Ganesh (2015-11-11 12:41:12)

bobbym · 2015-11-11 17:16:09

Hi;

Interesting, they changed over from Avogadro's number to Avogadro's constant.

Agnishom · 2015-11-11 19:43:03

I propose it should be called the avogadro nimber

Jai Ganesh · 2015-11-12 13:45:36

The initial singularity was the gravitational singularity of infinite density thought to have contained all of the mass and spacetime of the Universe before quantum fluctuations caused it to rapidly expand in the Big Bang and subsequent inflation, creating the present-day Universe. The initial singularity is part of the Planck epoch, the earliest period of time in the history of the universe.

Traditional models of the Universe

General relativity is used to predict that at the beginning of the Universe, a body containing all mass, energy, and spacetime in the Universe would be compressed to an infinitely dense point. The use of only general relativity to predict what happened in the beginnings of the Universe has been heavily criticized, as quantum mechanics becomes a significant factor in the high-energy environment of the earliest Universe, and general relativity on its own fails to make accurate predictions. In response to the inaccuracy of considering only general relativity, as in the traditional model of the Big Bang, alternative theoretical formulations for the beginning of the Universe have been proposed, including a string theory-based model in which two branes, enormous membranes much larger than the Universe, collided, creating mass and energy.

It is impossible to see the singularity or the actual Big Bang itself, as time and space did not exist inside the singularity and, therefore, there would be no way to transmit any radiation from before the Big Bang to the present day. However, evidence for the existence of an initial singularity, and the Big Bang theory itself, comes in the form of the cosmic microwave background and the continued expansion of the Universe.

Alternatives to the singularity

Various new models of what preceded and caused the Big Bang have been proposed as a result of the problems created by quantum mechanics. One model, using loop quantum gravity, aims to explain the beginnings of the Universe through a series of Big Bounces, in which quantum fluctuations cause the Universe to expand. This formulation also predicts a cyclic model of universes, with a new universe being created after an old one is destroyed, each with different physical constants. Another formulation, based on M-theory and observations of the cosmic microwave background, states that the Universe is but one of many in a multiverse, and has budded off from another universe as a result of quantum fluctuations, as opposed to our Universe being all that exists.

Jai Ganesh · 2015-11-12 22:41:26

Lists of stars by constellation

Stars are listed in the appropriate lists for the constellation, as follows:

Andromeda
Antlia
Apus
Aquarius
Aquila
Ara
Aries
Auriga
Boötes
Caelum
Camelopardalis
Cancer
Canes Venatici
Canis Major
Canis Minor
Capricornus
Carina
Cassiopeia
Centaurus
Cepheus
Cetus
Chamaeleon

Circinus
Columba
Coma Berenices
Corona Australis
Corona Borealis
Corvus
Crater
Crux
Cygnus
Delphinus
Dorado
Draco
Equuleus
Eridanus
Fornax
Gemini
Grus

Hercules
Horologium
Hydra
Hydrus
Indus

Lacerta
Leo
Leo Minor
Lepus
Libra
Lupus
Lynx
Lyra
Mensa
Microscopium
Monoceros
Musca
Norma
Octans
Ophiuchus
Orion
Pavo
Pegasus
Perseus
Phoenix
Pictor
Pisces

Piscis Austrinus
Puppis
Pyxis
Reticulum
Sagitta
Sagittarius
Scorpius
Sculptor
Scutum
Serpens
Sextans
Taurus
Telescopium
Triangulum
Triangulum Australe
Tucana
Ursa Major
Ursa Minor
Vela
Virgo
Volans
Vulpecula

Criteria of inclusion

Stars named with a Bayer, Flamsteed, HR, or Draper (not from the supplements) designation.
Stellar extremes or otherwise noteworthy stars.
Notable variable stars (prototypes, rare or otherwise important).
Nearest stars (<20 ly).
Stars with planets.
Notable neutron stars, black holes, and other exotic stellar objects/remnants.

Jai Ganesh · 2015-11-13 15:01:48

A parsec (symbol: pc) is a unit of length used to measure the astronomically large distances to objects outside the Solar System. One parsec is the distance at which one astronomical unit subtends an angle of one arcsecond. A parsec is equal to about 3.26 light-years (31 trillion kilometres or 19 trillion miles) in length. The nearest star, Proxima Centauri, is about 1.3 parsecs from the Sun. Most of the stars visible to the unaided eye in the nighttime sky are within 500 parsecs of the Sun.

The parsec unit was likely first suggested in 1913 by British astronomer Herbert Hall Turner. Named from an abbreviation of the parallax of one arcsecond, it was defined so as to make calculations of astronomical distances quick and easy for astronomers from only their raw observational data. Partly for this reason, it is still the unit preferred in astronomy and astrophysics, though the light year remains prominent in popular science texts and everyday usage. Although parsecs are used for the shorter distances within the Milky Way, multiples of parsecs are required for the larger scales in the universe, including kiloparsecs for the more distant objects within and around the Milky Way, megaparsecs for all but the closest galaxies, and gigaparsecs for many quasars and the most distant galaxies.

In August 2015, the IAU passed Resolution B2, which as part of the definition of a standardized absolute and apparent bolometric magnitude scale, included an explicit definition of the parsec as exactly

astronomical units, or approximately metres (based on the IAU 2012 exact SI definition of the astronomical unit). This corresponds to the small-angle definition of the parsec found in many contemporary astronomical references.

1 parsec ≈ 206264.81 astronomical units

metres
≈ 19.173512 trillion miles
≈ 3.2615638 light years.

Usage and measurement

The parallax method is the fundamental calibration step for distance determination in astrophysics; however, the accuracy of ground-based telescope measurements of parallax angle is limited to about 0.01 arcsecond, and thus to stars no more than 100 pc distant. This is because the Earth’s atmosphere limits the sharpness of a star's image. Space-based telescopes are not limited by this effect and can accurately measure distances to objects beyond the limit of ground-based observations. Between 1989 and 1993, the Hipparcos satellite, launched by the European Space Agency (ESA), measured parallaxes for about 100000 stars with an astrometric precision of about 0.97 milliarcsecond, and obtained accurate measurements for stellar distances of stars up to 1000 pc away.

ESA's Gaia satellite, which launched on 19 December 2013, is intended to measure one billion stellar distances to within 20 microarcseconds, producing errors of 10% in measurements as far as the Galactic Centre, about 8000 pc away in the constellation of Sagittarius.

Distances expressed in fractions of a parsec usually involve objects within a single star system. So, for example:

One astronomical unit (au), the distance from the Sun to the Earth, is just under

parsecs.
The most distant space probe, Voyager 1, was 0.0006 parsecs from Earth as of March 2015. It took Voyager 37 years to cover that distance.
The Oort cloud is estimated to be approximately 0.6 parsecs in diameter

The jet erupting from the active galactic nucleus of M87 is thought to be 1.5 kiloparsecs (4890 ly) long. (image from Hubble Space Telescope)

Parsecs and kiloparsecs

Distances expressed in parsecs (pc) include distances between nearby stars, such as those in the same spiral arm or globular cluster. A distance of 1000 parsecs (3262 light-years) is commonly denoted by the kiloparsec (kpc). Astronomers typically use kiloparsecs to express distances between parts of a galaxy, or within groups of galaxies. So, for example:

One parsec is approximately 3.26 light-years.
The nearest known star to the Earth, other than the Sun, Proxima Centauri, is about 1.30 parsecs (4.24 light-years) away, by direct parallax measurement.
The distance to the open cluster Pleiades is 130 ± 10 pc (420 ± 32.6 light-years) from us, per Hipparcos parallax measurement.
The centre of the Milky Way is more than 8 kiloparsecs (26000 ly) from the Earth, and the Milky Way is roughly 34 kpc (110000 ly) across.
The Andromeda Galaxy (M31) is ~780 kpc (~2.5 million light-years) away from the Earth.

Megaparsecs and gigaparsecs

A distance of one million parsecs is commonly denoted by the megaparsec (Mpc). Astronomers typically express the distances between neighbouring galaxies and galaxy clusters in megaparsecs.

Galactic distances are sometimes given in units of Mpc/h (as in "50/h Mpc"). h is a parameter in the range [0.5,0.75] reflecting the uncertainty in the value of the Hubble constant H for the rate of expansion of the universe: h = H / (100 (km/s)/Mpc). The Hubble constant becomes relevant when converting an observed redshift z into a distance d using the formula

.

One gigaparsec (Gpc) is one billion parsecs — one of the largest units of length commonly used. One gigaparsec is about 3.26 billion light-years, or roughly one fourteenth of the distance to the horizon of the observable universe (dictated by the cosmic background radiation). Astronomers typically use gigaparsecs to express the sizes of large-scale structures such as the size of, and distance to, the CfA2 Great Wall; the distances between galaxy clusters; and the distance to quasars.

For example:

The Andromeda Galaxy is about 0.78 Mpc (2.5 million light-years) from the Earth.
The nearest large galaxy cluster, the Virgo Cluster, is about 16.5 Mpc (54 million light-years) from the Earth.
The galaxy RXJ1242-11, observed to have a supermassive black hole core similar to the Milky Way's, is about 200 Mpc (650 million light-years) from the Earth.
The galaxy filament Hercules–Corona Borealis Great Wall, currently the largest known structure in the universe, is about 3 Gpc (10 billion light-years) across.
The particle horizon (the boundary of the observable universe) has a radius of about 14.0 Gpc (46 billion light-years).

Volume units

To determine the number of stars in the Milky Way, volumes in cubic kiloparsecs

are selected in various directions. All the stars in these volumes are counted and the total number of stars statistically determined. The number of globular clusters, dust clouds, and interstellar gas is determined in a similar fashion. To determine the number of galaxies in superclusters, volumes in cubic megaparsecs are selected. All the galaxies in these volumes are classified and tallied. The total number of galaxies can then be determined statistically. The huge void in Boötes is measured in cubic megaparsecs.

In cosmology, volumes of cubic gigaparsecs

are selected to determine the distribution of matter in the visible universe and to determine the number of galaxies and quasars. The Sun is the only star in its cubic parsec, but in globular clusters the stellar density could be from 100 to 1000 per cubic parsec.

Last edited by Jai Ganesh (2015-11-13 15:13:44)

bobbym · 2015-11-13 18:09:23

Hi;

Nice work on parsecs!

Jai Ganesh · 2015-11-13 19:00:32

Hi bobbym,

Thanks!!!

Jai Ganesh · 2015-11-16 01:35:29

The Sand Recokner

The "M" is a myriad, and represents 10,000. The Greek work is murious (uncountable, pl. murioi). The Romans converted to this to myriad.

The Sand Reckoner is a remarkable work in which Archimedes proposes a number system that uses powers of a myriad myriad (base 100,000,000) and is capable of expressing numbers up to

in modern notation.

He argues in this work that this number is large enough to count the number of grains of sand
which could be fitted into the universe.

"There are some, King Gelon, who think that the number of the sand is infinite in multitude; and I mean by the sand not only that which exists about Syracuse and the rest of Sicily but also that which is found in every region whether inhabited or uninhabited."

"Aristarchus of Samos brought out a book consisting of some hypotheses, in which the premises lead to the result that the universe is many times greater than that now so called. His hypotheses are that the fixed stars and the sun remain unmoved, that the earth revolves about the sun in the circumference of a circle, the sun lying in the middle of the orbit, and that the sphere of the fixed stars, situated about the same center as the sun, is so great that the circle in which he supposes the earth to revolve bears such a proportion to the distance of the fixed stars as the center of the sphere bears to its surface."

Archimedes took Aristarchus to mean that the ratio of the size of the earth to the size of the universe is comparable to that of the orbit of the earth compared to the sphere of stars.

"One can also show that the diameter of the universe is less than a line equal to a myriad diameters of the earth and that, moreover, the diameter of the universe is less than a line equal to one hundred myriad myriad stadia

ft, between Saturn and Uranus. As soon as one has accepted the fact that the diameter of the sun is not greater than thirty moon diameters and that the diameter of the earth is greater than the diameter of the moon, it is clear that the diameter of the sun is less than thirty diameters of the earth."

This was a huge leap over previous estimates of the size of the universe! Archimedes was the first person to think on the scale of modern astronomy.

". . . this number is the eighth of the eight numbers, which is one thousand
myriads of eight numbers. . . . It is therefore obvious that the number of grains of sand filling a sphere of the size that Aristarchus lends to the sphere of fixed stars is less than one thousand myriad myriad eighth numbers."

This is Archimedes' estimate of the

grains of sand to fill the universe.

Last edited by Jai Ganesh (2015-11-16 01:56:49)

Math Is Fun Forum

#26 2015-10-25 17:30:43

Re: Micro / Macro numbers in Science

#27 2015-10-25 18:03:39

Re: Micro / Macro numbers in Science

#28 2015-10-26 00:17:26

Re: Micro / Macro numbers in Science

#29 2015-10-26 05:56:36

Re: Micro / Macro numbers in Science

#30 2015-10-26 06:47:12

Re: Micro / Macro numbers in Science

#31 2015-10-26 14:20:53

Re: Micro / Macro numbers in Science

#32 2015-10-27 16:42:06

Re: Micro / Macro numbers in Science

#33 2015-10-28 07:00:47

Re: Micro / Macro numbers in Science

#34 2015-10-28 14:01:50

Re: Micro / Macro numbers in Science

#35 2015-10-28 14:56:01

Re: Micro / Macro numbers in Science

#36 2015-10-29 08:33:20

Re: Micro / Macro numbers in Science

#37 2015-10-29 12:13:28

Re: Micro / Macro numbers in Science

#38 2015-10-30 16:51:54

Re: Micro / Macro numbers in Science

#39 2015-10-31 17:17:03

Re: Micro / Macro numbers in Science

#40 2015-11-03 09:22:22

Re: Micro / Macro numbers in Science

#41 2015-11-07 10:39:37

Re: Micro / Macro numbers in Science

#42 2015-11-11 12:26:57

Re: Micro / Macro numbers in Science

#43 2015-11-11 17:16:09

Re: Micro / Macro numbers in Science

#44 2015-11-11 19:43:03

Re: Micro / Macro numbers in Science

#45 2015-11-12 13:45:36

Re: Micro / Macro numbers in Science

#46 2015-11-12 22:41:26

Re: Micro / Macro numbers in Science

#47 2015-11-13 15:01:48

Re: Micro / Macro numbers in Science

#48 2015-11-13 18:09:23

Re: Micro / Macro numbers in Science

#49 2015-11-13 19:00:32

Re: Micro / Macro numbers in Science

#50 2015-11-16 01:35:29

Re: Micro / Macro numbers in Science

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