Basic astronomical measurements plus astronomy units of measure.
Big Bang creates this universe: 13,700,000,000 years ago = 1.37e10 YA = 13.7 GYA = 0 y. The first singularity that we know of: Infinite density, temperature, pressure, etc., that was homogenous and isotropic. We don't know what came before the 1st singularity or how long it existed. It was the expansion of the first singularity, the Big Bang, that created the potential (difference, contrast, room), and that expansion continues today.
Planck epoch: 0 to 10^-43 s. The earliest period in time. One general force at the start, but by the end of this epoch there was gravity and the electronuclear force.
Grand unification epoch: 10^-43 s to 10^-36 s. Baryogenesis occurred, i.e. more matter than antimatter. By the end of this epoch there was gravity, strong interaction force, and electroweak interaction force.
Electroweak epoch: 10^-36 s to 10^-12 s. 10^28 K. Cosmic inflation occurs: The universe expanded by a factor of 10^26 linearly and 10^78 by volume.
Quark epoch: 10^-12 s to 10^-6 s. The four modern forces present: gravity, strong interaction, weak interaction, and electromagnetism. However the temperature is still to hot for quarks to form hadrons.
Hadron epoch: 10^-6 s to 1 s. Universe cools enough to for hadrons, including baryons such as protons and neutrons.
Lepton epoch: 1 s to 10 s. The hadrons and anti-hadrons annihilated each other. The Universe cooled enough to for leptons and anti-leptons to stop being formed and most of them annihilate each other.
Photon epoch: 10 s to 4 Ky. Photons dominate the universe. By the end of this epoch neutral hydrogen and helium atoms have formed by a recombination of charged electrons and proton. The reombination led to the decoupling of photons from matter leaving the protons free to travel, thus forming the famous Cosmic Microwave Background (CMB) radiation. Prior to the end of this epoch the universe was ionized and opaque, but by the end it was neutral and transparent.
Dark epoch: 4 Ky to 150 My. After the recombination (the 1st major phase change of hydrogen) and decoupling, but before the reionization (the 2nd major phase change). There were no light sources in this age other than the fading CMB radiation.
Reionization epoch: 150 My to 1 Gy. Quasars and stars start igniting, i.e. the neutral masses become ionized plasma. At the start of this epoch the universe was transparent, but by the end of the epoch it was 10% opaque.
Stelliferous era: 150 My to 100 Ty. The era of stars started in the Reionization epoch and is still going on.
First star: 150 My.
First galaxies: 700 My. The Milky Way galaxy is this old too.
Our sun and solar system formed: 9.14 Gy = 4.56 GYA.
Present: 13.7 Gy = 0 YA. The sun gets around 10% more luminous/hotter every 1 Gy.
Milky Way and Andromeda galaxies merge: 17 Gy.
Our sun becomes a red giant: 19.1 Gy = 5.4 Gy from now = 10 Gy old sun. All the hydrogen will have been converted to helium. Its size will extend beyond earth's current orbit.
Our sun becomes a white dwarf: 21.1 Gy = 7.4 Gy from now = 12 Gy old sun.
Local Group galaxies merge: 100 Gy to 1 Ty.
Galaxies outside of the Local Supercluser no longer observable: 2 Ty.
No more gas available to from new stars: 100 Ty.
Degenerate era: 100 Ty = 10^14 to 10^40 y. All stellar objects last until remnants decay.
Star formation ceases: 100 Ty = 10^14.
Planetary orbits decay: 1 Py = 10^15.
Stellar remnants escape galaxies or fall into black holes: 10^20 y.
Nucleons start to decay: 10^34 y.
All nucleons decay: 10^40 y.
Black Hole era: 10^40 y to 10^100 y.
Dark era: 10^100 y and beyond. Perpetual expansion, maximum entropy, heat death, no more potential.
Astronomy Units of Measure
A parsec (pc) stands for "PARallax of one arc SECond". If right triangle EDS has E=Earth, S=Sun, D=Distant object, and angle D is 1 arcsecond, then distance ES is 1 parsec. Roughly 1 pc = (360*60*60/2pi) AU = 206,265 AU = 3.08568e16 m = 30.8568 Pm = 3.2616 ly.
A astronomical unit (AU) is the mean radius of the Earth about the Sun. 1 AU = 149,597,870,691 m ~ 92.96e6 miles ~ 8.317 light minutes.
A light year (ly) is the distance covered by light in 1 year. Light travels at 299,792,458 m/s = 186,282.397 miles/s (or, as usually rounded, 300,000 km/s or 186,000 miles/s), thus 1 ly ~ 9.46e15 m ~ 9.46e12 Km ~ 5.88e12 miles ~ 63,241 AU.
Basic Astronomy Measurements
Age: Roughly 13.7 billion (13.7e9) years.
Number of Galaxies in the observable universe: Roughly 100 to 200 billion (1 to 2 e11).
Observable Diameter: 13.7 billion (13.7e9) ly.
The Virgo Supercluster.
Number of groups and clusters: Roughly 100, including the Local Group.
Mass: Roughly 10e15 Suns.
The Local Group.
Number of galaxies: 30, including its 3 largest: The Milky Way galaxy, the M31 (the Andromeda galaxy), and the smaller M33 (the Triangulum galaxy).
Diameter: Roughly 10 million (10e6) ly.
Nearest Galaxy: Andromeda Galaxy (aka Messier Object 31, M31, or NGC 224), roughly 2.9e6 ly = 920 Kpc away. It is a spiral galaxy in the direction of the Andromeda constellation.
Density of Intergalactic Medium (IGM): < 1 atom/ cm 3.
The Milky Way galaxy, aka The Galaxy.
Number of Stars: From the luminosity of our galaxy, it is estimated that our own Milky Way galaxy has 100 to 300 billion (1 to 3 e11) stars. The Milky Way galaxy has several dwarf galaxies orbiting it.
Diameter: ~100,000 (1e5) light years.
Mass: Roughly 1 trillion (1e12) Suns.
Density of Interstellar Medium (ISM): ~0.5 atoms / cm 3.
Width: 300 light years.
Distance from center of Galaxy: 8.6 Kpc ~ 26,000 ly ~ 2.5e17 Km
Location: In the Orion Arm (a minor spiral arm) located between the Perseus Arm and the Sagittarius Arm, two of the four major spiral arms.
Density: ~0.05 atoms / cm 3.
Density: ~0.1 atom / cm 3.
Contains several star system including our own Sun:
Alpha Centauri system. Composed of three stars: The Alpha Centauri binary system has A.C. A and A.C. B at 4.36 ly, while Proxima Centauri ~4.22 ly). The nearest to the sun and 4th brightest besides the Sun. In the constellation Centaurus, visible only from the southern hemisphere.
Sirius, ~8.58 ly. The 5th nearest to the Sun and the brightest besides the Sun.
Our Solar System:
Diameter: Assuming Pluto is the furthest planet, then the diameter is 39.5 AU. --> As of 2006, if we assume that Neptune is the furthest planet, then the diameter is roughly 30 AU.
Sun to Earth: 1 AU ~ 8.317 light minutes ~ 149,597,870,691 m ~ 149.6e6 Km ~ 92.96e6 miles.
Mercury: 0.4 AU, 0.055 Earth masses.
Venus: 0.7 AU, 0.815 Earth masses.
Earth: 1.0 AU, 1.0 Earth masses.
Mars: 1.5 AU, 0.107 Earth masses.
Asteroid Belt: 2.3-3.3 AU, ~0.001 Earth masses. The largest asteroid is Ceres at 2.7 AU, ~0.000159 Earth masses.
Jupiter: 5.2 AU, 318 Earth masses.
Saturn: 9.5 AU, 95 Earth masses.
Uranus: 14 AU, 14 Earth masses.
Neptune: 30 AU, 17 Earth masses.
Kuiper Belt: 30-50 AU, 0.3-30 Earth masses. Almost like a 2nd Asteroid Belt. Includes dwarf planets like the binary Pluto and Charon.
Oort Cloud: 50,000-100,000 AU = 0.8-1.6 ly, 5-100 Earth masses. Comets come from the Oort Cloud while comet-like "Centaurs" stay within the planetary orbits.
The Sun's solar winds goes as far as 130 AU.
Age: 5 billion (5e9) years out of the usual 10 billion for a class G2 star
Diameter: 1,392,000 Km = 109 Earths
Mass: 1.9891e30 Kg = 332,950 Earths
Surface Temperature: 5780 K
Core Temperature: 15,000,000 (1.5e7) K
Age: 4.5 billion (4.5e9) years
Equatorial Diameter: 12,756.28 Km ~7,926.385 miles
Equatorial gravity: 0.1564 Earths = 1.622 m * s -2.
1000+ Km = 620+ miles. Outer Space.
500 - 1000 Km = 310 - 620 miles. 2773 K = 2500 C = 4531 F at the top but gases are extremely sparse. The Exosphere is considered beyond the atmosphere. Composed primarily of Hydrogen and helium.
80 - 500 Km = 50 - 310 miles. 2273 K = 2000 C = 3631 F at the top but gases are sparse. The Thermosphere, aka Ionosphere, the "upper atmosphere". This layer is highly charged/ionized by solar radiation thus enabling radio waves to bounce off of this layer.
122 Km. The level that reentry from orbit begins.
100 Km = 62 miles. The Karman Line, the usual boundary between the atmosphere and Space. Aerodynamic surfaces no longer function.
80 Km. The U.S. calls its travelers that go beyond this level "astronauts".
50 - 80 Km = 30 - 50 miles. 200 K = -73 C = -100 F at the top. The Mesosphere, part of the "middle atmosphere". Meteors burn up in this layer.
80 Km = 50 miles. The upper boundary is the Mesopause.
7/17 - 50 Km = 4/10 - 30 miles. 270 K = -3 C = 26 F at the top. The Stratosphere, part of the "middle atmosphere".
50 Km = 31 miles. The upper boundary is the Stratopause.
45 Km = 28 miles. Ramjets no longer function.
32 Km = 20 miles. Turbojets no longer function.
24 - 40 Km = 15 - 40 miles. The Ozone Layer which absorbs UV radiation. This layer, if at 1 atm would only be a few mm thick.
24 Km = 15 miles. Regular aircraft pressurization systems no longer function.
20 Km = 12 miles. Bodily fluids spontaneously boil without pressurized environments.
0 - 7/17 Km = 0 - 4/10 miles. 220 K = -53 C = -64 F at the top. The Troposphere, "lower atmosphere", bulges at the equator. Has 75% of the atmosphere's mass. Contains what we call "weather" and the greenhouse effect.
7/17 Km = 4/10 miles. The upper boundary is the Tropopause.
14 Km = 8.7 miles = 45000 feet. Cruising height of Concordes or military jets.
9 Km = 5.6 miles = 30000 feet. Cruising height of most commercial jets.
5.3 Km = 3.3 miles. 50% of the atmosphere's mass is below this level.
3 Km = 2 miles. Supplemental oxygen for travelers required.