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2140 - Uranus is the 7th planet from the
Sun. All the rest of the planets spin
like tops as they orbit the Sun. But,
Uranus rolls on its side. It is the 3rd
largest planet and can be seen with the naked eye. Uranus orbits the Sun in 84 years with a
radius of 1,864 million miles. The Earth
orbits at 93 million miles. This great
distance means that sunlight is 1/400th that of Earth‘s.
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-
-
---------------------------------- 2140
- Uranus
-
- Uranus is the
7th planet from the Sun. All
the rest of the planets spin like tops as they orbit the Sun. But, Uranus rolls on its side. It is the 3rd largest planet and
can be seen with the naked eye. However,
it is exceedingly dim and seeing it is quite a challenge. Uranus was first discovered in 1781. It was the first planet discovered using a
telescope, a homemade telescope.
-
- Jupiter and
Saturn are known as the gas giants.
Uranus and Neptune are known as the ice giants. The atmosphere of Uranus is mostly hydrogen
and helium but it also contains water ice, ammonia ice, and methane ice, plus
some hydrocarbons. Ice is not surprising
since Uranus has the coldest atmosphere in the Solar System, -224F.
-
- ( See Review
2139 to learn about Neptune and its moon Triton)
-
- Uranus has 13
rings, 27 moons and a magnetosphere. It
is most unusual in the Solar System because its north pole points directly toward
the Sun. It orbits rolling on its
side. The wind speed on the surface is
560 miles per hour.
-
- Uranus orbits
the Sun in 84 years with a radius of 1,864 million miles. The Earth orbits at 93 million miles. This great distance means that sunlight is
1/400th that of Earth‘s.
-
- In the year 1783
orbit calculations were made but subsequent observations were always off what
was calculated. In 1841 astronomers
first suggested this discrepancy must be due to an unseen planet, Planet
X. In 1846 the new planet was discovered
exactly where calculations said it should be, it was named Neptune.
-
- Because of
Uranus’ 98 degree tilt one half of the planet is always in daylight. After half an orbit, 42 years, the other half
is in constant daylight. In between
these extremes the equator experience a
day-night cycle with a 17 hour rotation.
-
- The theory for
Uranus’ tilt is similar to the theory for the creation of our Moon. Uranus most likely suffered a massive
collision with another protoplanet during its early history.
-
- The Earth's
orbital and magnetic field are offset by 12
degrees. Uranus' are offset by 60
degrees. This results in a corkscrewing
magnetic field trailing millions of miles behind the planet.
-
- Uranus'
subtle rings are not like Saturn's bright icy rings. They are dark and reflect little light. The rings are probably mostly ice but covered
in organic methane and then baked dark by the radiation belt. Uranus' moons are similarly camouflaged as
well.
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- Two of the
moons, Cordelia and Ophelia, are shepherd moons. They orbit on either side of Uranus. Their gravitational pull herds the small
particles in the rings along their orbital path and keeps the rings from
dissipating into space.
-
- At current
count Uranus' has a total of 27 moons.
Some of the moonlets are only 2 to 9 miles diameter.
-
- We said
Uranus can be seen with the naked eye.
Naked eye visibility is put at an average Magnitude of +6.0, depending
on the individual. Uranus can appear
+5.6 to +5.9 Magnitude which is very dim.
Its angular diameter is 3.7 arc seconds.
Saturn is 20 arc seconds and Jupiter is 45 arc seconds for
comparison. Uranus mass is 14.5 that of
Earth‘s. Its density is 1.29 grams/cm^3.
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- Uranus’
magnetic field is tilted 59 degrees from the axis of rotation and does not
originate at the planet’s center. Theory
has it that the magnetic field is not generated by a molten, solid core, but,
rather by a water-ammonia ocean at some shallow depth under the surface.
-
- October 15, 2018. 1131
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------ “Jim Detrick” -----------
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--------------------- Monday, October 22, 2018 -------------------------
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