about one thousandth of the Sun's total mass, about three times the reduction in
mass computed above from fusion. In the course of pulling the Sun together, we
should take account of the work done increasing its temperature and compressing
it; but my crude sums indicate these are much smaller (of order exa tonnes).
""",
fullname = "Solar Constant",
neutrino=Quantity.fromDecimal(
65, units=10 * tera / metre**2, doc="""Solar neutrino flux at Earth.
This just counts how many neutrinos cross unit area, facing the sun, at 1 AU,
per unit time. No account is taken of the energy or momentum distributions
among these neutrinos. They are roughly one third each of the three types of
antineutrino. See Sun.bright for related observations.
""")),
wind=Object(speed=Quantity.flat(.3, .8, .4, mega * metre / second),
# I suppose that's speed at the Sun or Earth and it slows on its
# way out (c.f. study.space.Kuiper.Heliosphere).
# TODO: check back on unfinished page, for composition:
# http://solarscience.msfc.nasa.gov/feature4.shtml
source="Corona"),
discovery=Discovery("the earliest life-forms", -3e9), # etym ?
density = 1.409 * kg / litre,
age = Quantity(4.6e9, year, # Peter Francis, age of solar system [missing error bar]
lifespan = 1e18 * second, # Nuffield, order of magnitude
# remain could include a further c. 2e9 years as a white dwarf
remain = Quantity.fromDecimal(5, 0, 9, year)),
magnitude = Quantity.flat(4.79, 4.83), # K&L, Moore
aliases = ('Sol',))
According to http://www.xs4all.nl/~mke/Gliese710.htm this is a red dwarf
headed our way at 50,400 km/hr, 50 times the size of Earth, 100,000 times as
massive and due to arrive in about 1.4 mega years. However, solstation
reports that astronomers don't expect it to disturb the Oort cloud enough to
'create a substantial increase in the long-period comet flux at Earth's
orbit'.
Apparently, we're also due (not quite so close, but nearer than Proxima
Centauri, our current nearest neighbour) visits from Barnard's star (10,000
years hence) and α Centauri (A/B).\n""")
Gliese710.Solstation(
'K5-M1 V',
Float(63, 1),
'18:19:50.8-1:56:19.0',
Quantity.flat(.4, .6, .42),
# but xs4all.n./~mke gave 1e5 * Earth.mass
Float(4.2, 1, -2),
Float(.67, 1), # 'possibly 67 percent'
aliases=('NSV 10635', 'Gl 710', 'Hip 89825', 'BD-01 3474', 'HD 168442',
'HD 168442', 'U449', 'Vys/McC 63'),
# http://www.solstation.com/stars2/gl710.htm
# gives "within 1.1 ly (0.34 pc)"; i.e. c. 7e4 AU
closestapproach=4e4 * AU)
Centaur.Alpha = System(
"α Centauri",
__doc__="""α Centauri has been known since ancient times.
It's the fourth brightest star in the night sky as well as the brightest star
in constellation Centaurus; it's been known about for millennia.\n""",
__doc__ = """Gliese 710
According to http://www.xs4all.nl/~mke/Gliese710.htm this is a red dwarf
headed our way at 50,400 km/hr, 50 times the size of Earth, 100,000 times as
massive and due to arrive in about 1.4 mega years. However, solstation
reports that astronomers don't expect it to disturb the Oort cloud enough to
'create a substantial increase in the long-period comet flux at Earth's
orbit'.
Apparently, we're also due (not quite so close, but nearer than Proxima
Centauri, our current nearest neighbour) visits from Barnard's star (10,000
years hence) and α Centauri (A/B).\n""")
Gliese710.Solstation('K5-M1 V', Float(63, 1),
'18:19:50.8-1:56:19.0',
Quantity.flat(.4, .6, .42),
# but xs4all.n./~mke gave 1e5 * Earth.mass
Float(4.2, 1, -2),
Float(.67, 1), # 'possibly 67 percent'
aliases=('NSV 10635', 'Gl 710', 'Hip 89825', 'BD-01 3474',
'HD 168442', 'HD 168442', 'U449', 'Vys/McC 63'),
# http://www.solstation.com/stars2/gl710.htm
# gives "within 1.1 ly (0.34 pc)"; i.e. c. 7e4 AU
closestapproach = 4e4 * AU)
Centaur.Alpha = System("α Centauri",
__doc__="""α Centauri has been known since ancient times.
It's the fourth brightest star in the night sky as well as the brightest star
in constellation Centaurus; it's been known about for millennia.\n""",
aliases=("Rigil Kentaurus",),
92 * mega * metre,
Columbo=Hoop("Columbo Gap", Saturn, 77.8 * mega * metre, width=100 * km),
Maxwell=Hoop("Maxwell Gap", Saturn, 87.5 * mega * metre, width=270 * km))
Ring("Saturn's B Ring", Saturn, 92 * mega * metre, 117.58 * mega * metre)
Ring(
"The Cassini Division",
Saturn,
117.58 * mega * metre,
122.2 * mega * metre,
width=4.7 * mega * metre,
note=
"gap between rings, not actually a ring; and not actually quite empty, either",
Huygens=Hoop("Huygens Gap",
Saturn,
117.58 * mega * metre,
width=Quantity.flat(285, 440, None, km)))
Ring("Saturn's A Ring",
Saturn,
122.2 * mega * metre,
136.78 * mega * metre,
Encke=Hoop("Encke Division",
Saturn,
133.57 * mega * metre,
width=325 * km),
Keeler=Hoop("Keeler Gap", Saturn, 136.53 * mega * metre, width=35 * km))
Ring(
"Saturn's F Ring",
Saturn,
140.0875 * mega * metre,
140.3525 * mega * metre,
# radius 140.22 Mm, width 30 to 500 km
about one thousandth of the Sun's total mass, about three times the reduction in
mass computed above from fusion. In the course of pulling the Sun together, we
should take account of the work done increasing its temperature and compressing
it; but my crude sums indicate these are much smaller (of order exa tonnes).
""",
fullname = "Solar Constant",
neutrino=Quantity.fromDecimal(
65, units=10 * tera / metre**2, doc="""Solar neutrino flux at Earth.
This just counts how many neutrinos cross unit area, facing the sun, at 1 AU,
per unit time. No account is taken of the energy or momentum distributions
among these neutrinos. They are roughly one third each of the three types of
antineutrino. See Sun.bright for related observations.
""")),
wind=Object(speed=Quantity.flat(.3, .8, .4, mega * metre / second),
# I suppose that's speed at the Sun or Earth and it slows on its
# way out (c.f. study.space.Kuiper.Heliosphere).
# TODO: check back on unfinished page, for composition:
# http://solarscience.msfc.nasa.gov/feature4.shtml
source="Corona"),
discovery=Discovery("the earliest life-forms", -3e9), # etym ?
density = 1.409 * kg / litre,
age = Quantity(4.6e9, year, # Peter Francis, age of solar system [missing error bar]
lifespan = 1e18 * second, # Nuffield, order of magnitude
# remain could include a further c. 2e9 years as a white dwarf
remain = Quantity.fromDecimal(5, 0, 9, year)),
magnitude = Quantity.flat(4.79, 4.83), # K&L, Moore
aliases = ('Sol',))
from outer import Neptune
from common import Orbit, Spin, Discovery, Spheroid, Surface
from rock import NASAmoon, NASAshell
from body import Object, Ring, Shell, Planetoid, MinorPlanet, DwarfPlanet
Float = Quantity.fromDecimal
About = Quantity.within
Pluto = KLplanet('Pluto',
KLsurface(.23, .05, Spin(6 * day + 9 * hour, 118),
flattening = 0, material="CH4 ice",
temperature=Centigrade(About(-233, 5))),
Orbit(Sun, Float(5936, 1, 9, metre),
Spin(250 * year, 17.13), .253),
.0025,
Quantity.flat(1.8, 2.1), # according to Solstation (K&L gave 1.1 g/cc)
DwarfPlanet, # in place of Planet
atmosphere="trace CH4",
discovery=Discovery('Clyde Tombaugh', 1930,
date="1930 February 18 or 23",
location="Lowell observatory, Flagstaff, Arizona",
story="""Discovery of Pluto
Lowell, among others, noticed that the orbits of Neptune and Uranus wobbled,
hinting at another planet further out. Lowell predicted the planet's orbit and
set in motion a project to find it - which continued after his death and lead to
successful discovery.
The telescope which took the discovery pictures was only installed in 1929 (on
'Mars Hill' no less).
"""))
from body import Object, Ring, Shell, Planetoid, MinorPlanet, DwarfPlanet
Float = Quantity.fromDecimal
About = Quantity.within
Pluto = KLplanet(
'Pluto',
KLsurface(.23,
.05,
Spin(6 * day + 9 * hour, 118),
flattening=0,
material="CH4 ice",
temperature=Centigrade(About(-233, 5))),
Orbit(Sun, Float(5936, 1, 9, metre), Spin(250 * year, 17.13), .253),
.0025,
Quantity.flat(1.8, 2.1), # according to Solstation (K&L gave 1.1 g/cc)
DwarfPlanet, # in place of Planet
atmosphere="trace CH4",
discovery=Discovery('Clyde Tombaugh',
1930,
date="1930 February 18 or 23",
location="Lowell observatory, Flagstaff, Arizona",
story="""Discovery of Pluto
Lowell, among others, noticed that the orbits of Neptune and Uranus wobbled,
hinting at another planet further out. Lowell predicted the planet's orbit and
set in motion a project to find it - which continued after his death and lead to
successful discovery.
The telescope which took the discovery pictures was only installed in 1929 (on
'Mars Hill' no less).
SAOmoon(Saturn, _kav, "S9", 18486, 939.90)
SAOmoon(Saturn, _kav, "S10", 17452, 860.03)
SAOmoon(Saturn, Discovery("Holman", 2000), "S11", 17874, 888.54)
SAOmoon(Saturn, _glad, "S12", 19747, 1038.11)
# http://antwrp.gsfc.nasa.gov/apod/ap20071024.html
Ring("Saturn's D Ring", Saturn, 67 * mega * metre, 74.5 * mega * metre)
Ring("Saturn's C Ring", Saturn, 74.5 * mega * metre, 92 * mega * metre,
Columbo=Hoop("Columbo Gap", Saturn, 77.8 * mega * metre, width=100 * km),
Maxwell=Hoop("Maxwell Gap", Saturn, 87.5 * mega * metre, width=270 * km))
Ring("Saturn's B Ring", Saturn, 92 * mega * metre, 117.58 * mega * metre)
Ring("The Cassini Division", Saturn, 117.58 * mega * metre, 122.2 * mega * metre,
width = 4.7 * mega * metre,
note="gap between rings, not actually a ring; and not actually quite empty, either",
Huygens=Hoop("Huygens Gap", Saturn, 117.58 * mega * metre,
width=Quantity.flat(285, 440, None, km)))
Ring("Saturn's A Ring", Saturn, 122.2 * mega * metre, 136.78 * mega * metre,
Encke=Hoop("Encke Division", Saturn, 133.57 * mega * metre, width=325 * km),
Keeler=Hoop("Keeler Gap", Saturn, 136.53 * mega * metre, width=35 * km))
Ring("Saturn's F Ring", Saturn, 140.0875 * mega * metre, 140.3525 * mega * metre,
# radius 140.22 Mm, width 30 to 500 km
width=Quantity.flat(30, 500, None, km))
Ring("Saturn's E Ring", Saturn, 180 * mega * metre, 480 * mega * metre)
# Average thickness: c. 100 m. If all gathered together, they'd form a body
# only 500 km in diameter (and the NASA book uses "diameter", in some of its
# data tables, as a synonym for "radius" - d'oh). Diagrams also show an
# "unnamed" object in orbit at 118 Mm, shepherding the B ring.
del Discovery, Ring, Hoop, NASAmoon, NASAshell, NASAtrojan, SAOmoon, _glad, _kav, _tmp, \
mega, metre, km, Quantity
