Neptune is the eighth planet from the Sun and the last of the known planets. While it is the third largest planet with respect to mass, it is only the fourth largest in terms of diameter. Due to its blue coloration, Neptune was named after the Roman god of the Sea. Neptune is called Poseidon in Greek, continuing the link to the sea. But sorry there is only the colour of the sea associated with this planet, not any hint of waters as such.
It takes Neptune 164.8 Earth years to orbit the Sun. On 11 July 2011, Neptune completed its first full orbit since its discovery in 1846. Neptune has the second largest gravity of any planet in the solar system – second only to Jupiter. The orbit path of Neptune is approximately 30 astronomical units (AU) from the Sun. This means it is around 30 times the distance from the Earth to the Sun. The largest Neptunian moon, Triton, was discovered just 17 days after Neptune itself was discovered. Neptune has a storm similar the Great Red Spot on Jupiter. It is commonly known as the Great Dark Spot and is roughly the size of Earth. Neptune also has a second storm called the Small Dark Spot. This storm is around the same size as Earth’s moon. Neptune spins very quickly on its axis. The planet’s equatorial clouds take 18 hours to complete one rotation. The reason this happens is that Neptune does not have a solid body. It is one of the gas giants. The climate on Neptune is extremely active. In its upper atmosphere, large storms sweep across it and high-speed solar winds track around the planet at up to 1,340 km per second. Like the other outer planets, Neptune possesses a ring system, though its rings are very faint. They are most likely made up of ice particles and grains of dust with a carbon-based substance coating them.Neptune has 14 known moons. The largest of these moons is Titan – a frozen world which spits out particles of nitrogen ice and dust from below its surface. It is believed that Titan was caught by the immense gravitational pull of Neptune.
Only one spacecraft, the Voyager 2, has flown past Neptune. It happened in 1989 and captured the first close-up images of the Neptunian system. It took 246 minutes – four hours and six minutes – for signals from Voyager 2 to reach back to Earth. Until the Voyager 2 spacecraft fly-by little was known about Neptune. This mission provided new information about Neptune’s rings, number of moons, atmosphere and rotation.
When scientific discoveries are made there is often a debate as to who deserves credit. The discovery of Neptune is one such example. Shortly after the discovery of the planet Uranus in 1781, scientists noticed that its orbit had significant fluctuations that were not expected. To solve this mystery, they proposed the existence of another planet whose gravitational field would account for such orbital variances. In 1845, the English astronomer John Couch Adams completed his calculations as to the position of this unknown planet. Although he submitted his findings to the Royal Society (the leading English scientific organization), his work was met with little interest. However, a year later the French astronomer Jean Joseph Le Verrier made known his calculations that were strikingly similar to those of Adams. As a result of the two men’s independent estimates being so close, the scientific community took notice and began its search for the planet in the region of the sky Adams and Le Verrier had predicted. On September 23, 1846, the German astronomer Johann Gall observed the new planet near to where Adam’s calculations had forecasted and even closer to those of Le Verrier. Le Verrier was initially given credit for the discovery. Eventually both men were given credit.
Neptune’s upper atmosphere is composed of 80% hydrogen, 19% helium and 1% methane. Similar to Uranus the blue coloration of Neptune is due in part to its atmospheric methane, which absorbs light having a wavelength corresponding to red. Unlike Uranus, Neptune is a deeper blue, and, therefore, some other atmospheric component must be present in the Neptunian atmosphere that is not found in Uranus’ atmosphere.
Two significant weather patterns have been observed on Neptune. The first, seen during the Voyager 2 fly-by mission, are the Dark Spots. These are storms comparable to the Great Red Spot found onJupiter. However, a difference between these storms is their duration. Whereas the Great Red Spot has lasted for centuries, the Dark Spots are much more shortly lived as is evident by their disappearance when Neptune was viewed by the Hubble SpaceTelescope just four years after the Voyager 2 fly-by.
As with the othergas giants, Neptune’s atmosphere is divided into latitudinal bands. The wind speed achieved in some of these bands is almost 600 m/s, the fastest known in the Solar System.This apart from the high speed solar winds that roar around the planet mentioned above. Its atmosphere also contains icy clouds and the fastest winds recorded in the solar system. Particles of icy methane and minor gases in the extremities of the atmosphere give Neptune its deep blue colour. The striking blue and white features of Neptune also help to distinguish it from Uranus.
Neptune’s atmosphere is subdivided into the lower troposphere and the stratosphere with the tropopause being the boundary between the two. In the lower troposphere temperatures decrease with altitude however they increase with altitude in the stratosphere. Hydrocarbons form hazes of smog that appear in the entire upper atmosphere of Neptune and hydrocarbon snowflakes that form in Neptune’s atmosphere melt before they reach its surface due to the high pressure. Neptune is regarded as having the coldest temperatures in our solar system. Neptune itself has an average surface temperature of -214°C, approximately 353°F. It’s moon Triton is the coldest known object in the Solar System with a recorded surface temperature of -235° C
The interior of Neptune, similar to that of Uranus, is made of two layers: a core and mantle. The core is rocky and estimated to be 1.2 times as massive as the Earth. The mantle is an extremely hot and dense liquid composed of water, ammonia and methane. The mantle is between ten to fifteen times the mass of the Earth.
Although Neptune and Uranus share similar interiors, they are, however, quite distinct in one way. Whereas Uranus emits only about the same amount of heat that it receives from the Sun, Neptune emits nearly 2.61 times the amount of the sunlight it receives. To place this in perspective, the two planets’ surface temperatures are approximately equal, yet Neptune receives only 40% of the sunlight that Uranus does. Additionally, this large internal heat is also what powers the extreme winds found in the upper atmosphere.
ORBIT & ROTATION
With the discovery of Neptune, the size of the known Solar System increased by a factor of two. With an average orbital distance of 4.50 x 109 km, it takes sunlight almost four hours and forty minutes to reach Neptune. Moreover, this distance also means that a Neptunian year lasts about 165 Earth years!
Like Jupiter and Saturn, Neptune rotates very quickly as compared to the planets in our Solar System. With a rotational period of a little over 16 hours, Neptune has the third shortest day in the Solar System.The axial tilt of Neptune is 28.3°, which is relatively close to the Earth’s 23.5°. What is amazing is that, even at such a far distance from the Sun, Neptune still experiences seasons more similar to those on Earth as a result of its axial tilt.
MOONS AND RINGS
Currently, Neptune is known to have thirteen moons. Of these thirteen only one is large and spherical in shape. This moon, Triton, is believed to have originally been a dwarf planetcaptured by Neptune’s gravitational field, and, thus, not a natural satellite of the planet. Evidence for this theory comes from Triton’s retrograde orbit of Neptune; that is, Triton orbits in the opposite direction that Neptune rotates. Neptune has three major rings – Adams, Le Verrier and Galle– named after the three astronomers who had a hand in finding the planet. Thisring system is much fainter than that of the other gas giants. In fact, some of the rings are so dim that it was believed at one time that they were incomplete. However, images from the Voyager 2 fly-bys show extremely faint rings.
Neptune’s Great Dark Spot
The Great Dark Spot in the southern atmosphere of Neptune was first discovered in 1989 by the Voyager 2 spacecraft. It was an incredibly large rotating storm system with winds of upto 1,500 miles per hour, the strongest winds recorded on any planet. How such powerful winds were discovered on a planet so far from the sun is still considered a mystery to this day. Data from the Voyager 2 spacecraft also showed that the Great Dark Spot varied significantly in size during their brief pass of the planet. When Neptune was viewed by the Hubble Space telescope in 1994 the Great Dark Spot had vanished, although a different dark spot had appeared in Neptune’s northern hemisphere.
Now let’s sum up the conditions on Neptune that preclude the existence of life:
As with all gas giants from Jupiter outward there is no planetary surface on which to land. The lack of oxygen in the planets atmospheric make-up negates the likelihood of any life as we know it from existing on this planet. Human life, animal life or planet life are all excluded. Like Uranus, the fact that this planet has a dark blue tinge belies that fact that it is hostile to human life. The temperatures which exist on Neptune are barriers to life forms we are familiar with as are the winds at the “surface” level of the planet. I placed “surface” in inverted commas because it does not have an inhabitable core. The pressures recorded in the interior of Neptune as judged to crush any life found there. The high speed solar winds that swirl around Neptune would thwart any attempt to approach the planet in a space craft to effect a controlled landing. Given the fact that the planet has the fastest wind speeds in the solar system is a strong factor encouraging us to stay away. The fact that this planet is the coldest in our solar system does not bode well for our hopes of finding life of the planet nor forging a life on the planet by setting up a colony. Life on Neptune – forget it.
My conclusion having done all this research is that it is best for us to head back to the warm climes of Earth and be satisfied with where God has placed us. Neptune is the least well known planet given the fact that we only have data collected over the four hours of Voyager 2 flying by and anything we have gained since by observation from afar via the Hubble Space Telescope. Voyager 2 has gone further off into deep space and will not return and then there are no plans to send any further space craft to Neptune. Our search for life or extra-terrestrial intelligence in the environs of Neptune has ended.
Next Nugget I will focus on more of the amazing features of Earth as our perfect place to live. I think we had better consider taking better care of this planet. It’s the only one likely for us to live on and God did place mankind here to care for it well. Oops.