Planets

Planets

Given that the Big Bang is the source of all that we see (as well as “other universes”), it is rewarding to be able to view and photograph items in our universe that reveal this process. A physicist was once asked, “What existed before the Big Bang?” His response was that while he was not sure, he did feel that the Laws of Physics were there. Simple photographs of the planets support the presence of the laws of physics during the formation of the universe that we see.

The planets are within our solar system. Orbital distances range from 57.909(10)^6 km (36 million miles) for Mercury (nearest to the sun) to 5915.8 (10)^6 km (3700 million miles) for Pluto (Neptune is near to that). Mercury is one of the rocky innermost planets, along with Venus, Earth and Mars. Mercury is small, has an iron core like Earth. Since its orbit is very near to the Sun, it is most easily visible in the evening, as the Sun is setting. Venus is a cloud covered solid planet that orbits between the Earth and the Sun. Because of this, we can see phases as seen on the Moon. Galileo offered this as proof that the Copernican system of the universe was correct. It can also appear from Earth in the first few hours prior to sunrise; it is the morning star. Mars is a hard, rocky planet that is the next outer orbit after Earth. It has a red appearance because of the soil. Discoveries from the several recent probes of the planet have shown many similarities with Earth, including the high likelihood of water being present at some time in its history and some indications of life forms. It has polar ice caps that change with the season, and heavy dust storms that obscure visibility. Keep watch for the latest from the NASA probes. Uranus and Neptune are the giant planets that are the most distant in our solar system. While Uranus and Neptune are very large, their distance from Earth makes them very small in the sky. In small telescopes, they may be observed as small objects in photographs. They are seen to be moving in a planetary motion, unlike the star field. My only photo of Uranus is with it as a small star like dot amongst other stars. It was identified by noting that it moved differently from the stars. Details on the other planets follows.

The gravitational forces described by Sir Isaac Newton in 1687 largely determine the shape and position of the planets. It is not surprising that Newton the mathematician followed Galileo the experimentalist by just over 50 years. Newton made contributions to telescope technology and mathematical analysis to support understanding of the universe.

Venus

Venus is an innermost planet, i.e its orbit is between Earth and the Sun. Because of its proximity to the Sun, it is often hidden from view from the Earth, either by the Sun’s glare or the Sun itself. It is visible as either an evening planet or a morning planet. The video below was assembled from 24 still images collected from 5:43 pm to 5:55 pm 17 Dec 2013, just at dusk. Note that initially the planet is not visible, mostly because of the lack of contrast between Venus and the sky. Then, as the Earth continues its rotation to the East, the Sun sets and the sky darkens and Venus suddenly pops into view. As time progresses and Venus moves downward in the West, toward the horizon, as the sky further darkens.

http://www.debclltx.com/wp-content/uploads/2013/12/Venus121713B.mov

Jupiter

The different views that we have seen on Jupiter led to some curiosity about the meaning of the colors and depths in these photos. The following is composed from several sources, including the page Nine Planets which is a very extensive report on all of the planets. Their information is developed from the various probes and telescopic analyses of the planet.

It is well known that Jupiter is mostly gas, with a small but very dense solid core. The chemical makeup is 90% hydrogen and 10% helium with the rest ammonia and rock. The core is liquid metal hydrogen and the outermost layers are ordinary molecular hydrogen and helium.

What we see is the atmosphere, which is on top of this very deep outer layer. The atmosphere mixes in some tiny amounts of water, carbon dioxide and methane. There are three distinct layers of clouds, namely ammonia ice, ammonia hydroxide and a mixture of ice and water. The colors that we see correlate with the altitudes of the clouds with blue the lowest, and brown and whites intermediate and reds highest. The vivid colors seen in Jupiter’s clouds are probably the result of subtle chemical reactions of the trace elements in Jupiter’s atmosphere, perhaps involving sulfur whose compounds take on a wide variety of colors, but the details are unknown. The texture of what we see is driven by the high velocity winds. Bands travel in opposite directions and generate the vortices identified as the Red Spots. They change appearance with time, i.e. the thickness and color of the bands as well as the Red Spots change.

I captured the great Red Spot once (081609) and in others show the changing features of the bands. Jupiter has four significant (Galilean) moons, and a total of 16 moons, in a synchronous orbit. Io is the innermost moon (orbit of 1 day, 18 hours) followed by Europa (3d, 13h), Ganymede (7d, 3h( and Callisto (16d, 16h).These winds are driven by internal heat exiting the planet at different latitudes. One photo shows three of Jupiter’s moons and another shows one of Jupiter’s moons (Ganymede) along with the shadow of Io on the planet.

If you have read down this far then you might have an interest in more detail about Jupiter. Christopher Go does an almost daily photographic session with comments on the changes occurring in the band thickness, location and color. He can be accessed at

http://astro.christone.net/jupiter

Saturn

Saturn provides contrasts and image opportunities for both the amateur astrophotographer and one who is curious about the creation of the universe. Even though the rings are the most striking feature, the mass of the disk is what sets the foundation for the planet. Hydrogen is the dominant chemical element in both of the gas planets, Jupiter and Saturn. While Saturn is smaller than Jupiter (it occupies 60 percent of the volume of Jupiter), it has only a third of the mass and has a density of seventy percent that of water. Hence, it would float if dropped in a very large tub of water. The atmospheres that we see in the two are similar. In Saturn the hazy brown clouds are composed mostly of hydrogen and helium and methane with ammonia, hydrogen sulfide and water. They form circulation bands, which vary about the latitude and are symmetric about the equator. The patterns of the atmospheric bands in the gas planets are determined by dynamic interaction between the surface of the planet and the atmosphere. Storms occur that disrupt the pattern, but the overall symmetry generally holds.

The main rings are labeled A, B and C, although there are a total of 8 rings consisting of very small (i.e. dust spec sized) particles as well as some the size of a house. They are maintained in the orbit by a combination of gravitational attraction and momentum. Equilibrium in the ring particles is sometimes interrupted by impacts from asteroids. In fact, an interesting periodic ripple pattern in the ring particles resulted from a recent asteroid impact. It has since died away. A comparison of images of Saturn at different times shows that the rings are elevated at different times, indicating that the planet is precessing, as experienced by most other planets. The planet precesses (i.e. the axis of rotation oscillates) as well as rotates. With this the rings have a 15 year cycle.

Material presented here is from several sources, including “Saturn”. Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2012. Web. 31 Dec. 2012. Other sources are the NASA probes including Pioneer 10 and 11 probes in the 1970’s (Sky & Telescope, July 2006, pg. 20), followed by Voyagers 1 and 2 and finally the Cassini-Huygens probe in 2004. Other telescopes have produced very detailed images of both planets. The Huygens probe landed on the moon Titan and was the first to land on a planet’s moon, other than ours.

It is reassuring that the formations seen by these powerful telescopes are confirmable by amateur astronomers. For example, the turbulence caused by the different rotational speeds of the bands on Jupiter results in shear in the Equatorial Zone which can be imaged with modest amateur telescopes. This shear also leads to the Red Spots, which also can be imaged by amateurs.

Another interesting fact is that the orbit of the moons of Jupiter was a key player in Galileo confirming Copernicus theory of a heliocentric universe. Since the Jupiter moons clearly rotated around Jupiter, and not the Earth, the earth-centered universe was seriously questioned. Jupiter’s moons Io, Europa and Ganymede are locked together in a 1:2:4 orbital resonance and their orbits evolve together. Callisto is almost part of this, and will be in a few hundred million years.

The table in the Appendix shows that even though Jupiter is mostly gas, it’s mass combined with its moons is still great compared to the other planets and their moons orbiting the Sun.