Recently (same as Planet Uranus), I had an opportunity to see the rarely-viewable (from Earth) planetary neighbors of Earth . . . Neptune.
THE PLANET NEPTUNE AND SCIENTIFIC FACTS
Before attempting to find the planet, I researched some of the greatest characteristics of this large, sapphire-blue planet in our Solar System. I wanted to know how similar it was to other comparable planets.
Neptune is the 8th planet from the Sun (second from the right), orbiting at a distance of 4.5 billion km. It is one of the “Jovian Planets”, the large planets with gaseous atmospheres that consists of Jupiter, Saturn, and Uranus.
Neptune was discovered on September 23, 1846 by Urbain Le Verrier. There were two others who claimed to discover the planet at the same time, but while all three viewed the planet. It was Le Verrier that received confirmation by the astronomical community and the right to name the planet . . . Neptune.
In Roman mythology, Neptune was the god of the sea (called Poseidon in Greek). The demand for a mythological name kept with the tradition of the other planets being named for Greek and Roman mythology. Most languages today use some variant of the name “Neptune” for the planet. Earth is thus far the only Solar System planet without a Roman or Greek mythological name.
Pluto was once considered the most distant planet, In a controversial decision, the IAU passed a mandate which states a planet to be a celestial body orbiting a star with enough mass to be rounded by its own gravity but has not cleared its neighboring region of planetesimals, is not a satellite, and it has to have sufficient mass to overcome its compressive strength and achieve hydrostatic equilibrium. On this Pluto was “demoted” to the status of “dwarf planet” instead. At some point this might change but until then, Neptune is officially the most distant.
This graphic gives some quick facts at a glance, but the diameter listed is impossible (and likely a typo).
With an equatorial radius of 24,764 km, Neptune 3.9 times larger than Earth, yet smaller than all the other gas giants in the Solar System. But Neptune is actually more massive than Uranus by about 18%. Since it’s smaller but more massive, Neptune has a much higher density than Uranus. With a density of 1.638 g/cm^3, Neptune is the densest of the gas giants.
At the top of its clouds, temperatures on Neptune can dip down to 51.7 Kelvin, or -221.45 degrees Celsius (-366.6 °F). That’s almost three times the coldest temperature ever recorded on Earth (-89.2°C; -129°F).
A day on Neptune lasts 16 hrs and 6 minutes compared to Earth, and just one season lasts 41 1/2 Earth-years versus the seasons of Earth that are only around 3 months (or 0.25 Earth-years).
The atmosphere of Neptune is similar to all the large planets in the Solar System; it mostly consists of hydrogen and helium, with trace amounts of methane, water, ammonia and other ices. But unlike the other gas planets in the Solar System, Neptune’s atmosphere has a larger proportion of the ices. It’s the methane in the planet’s upper atmosphere that give it its bright blue color.
The light we see from Neptune is actually the reflected light from the Sun. Although the entire spectrum of light hits Neptune, the small amount of amount of methane absorbs light from the red end of the spectrum, while allowing the blue light to bounce back out. The color of Neptune’s atmosphere is brighter than Uranus, which has a similar atmosphere and astronomers are not yet sure why there’s such a dramatic color difference.
As with the other planets, the atmosphere of Neptune is broken up into distinct bands of storms. The fastest winds in the Solar System occur at Neptune – clocked at 2,400 km/h (1,500 miles per hour . . . or 2 times the speed of sound in Earth’s atmosphere). Some storms can grow large and remain for long periods of time. Neptune has its own Great Dark Spot, similar to the Great Red Spot on Jupiter.
In the summer of 1989, NASA’s Voyager 2 became the first spacecraft to observe the planet Neptune, its final planetary target. Passing about 4,950 kilometers (3,000 miles) above Neptune’s north pole, Voyager 2 made its closest approach to any planet 12 years after leaving Earth in 1977. Five hours later, Voyager 2 passed about 40,000 kilometers (25,000 miles) from Neptune’s largest moon, Triton, the last solid body the spacecraft will have an opportunity to study.
Neptune has 14 known moons, named after lesser sea gods and nymphs from Greek mythology. The largest by far is Triton, whose discovery on Oct. 10, 1846, was in a sense enabled by beer — amateur astronomer William Lassell used the fortune he made as a brewer to finance his telescopes.
Triton is the only spherical moon of Neptune — the planet’s other 13 moons are irregularly shaped. It is also unique in being the only large moon in the solar system to circle its planet in a direction opposite to its planet’s rotation — this “retrograde orbit” suggests that Triton may once have been a dwarf planet that Neptune captured rather than forming in place, according to NASA. Neptune’s gravity is dragging Triton closer to the planet, meaning that millions of years from now, Triton will come close enough for gravitational forces to rip it apart.
In 2013, scientists caught sight of Neptune’s “lost” moon of Naiad using data from the Hubble Space Telescope. The 62-mile-wide (100 km) moon had remained unseen since Voyager 2 discovered it in 1989. In the same year, scientists using the Hubble Space Telescope found the 14th moon, designated “S/2004 N 1”. It is Neptune’s smallest moon and is just 11 miles (18 km) wide. It has not been given an official name yet by the Astronomical community.
The Neptune is not visible without a telescope from Earth. Due to the distance of Neptune away from Earth, Neptune can only be viewed with high powered telescopes.
Where Uranus is a little less than 20 AU away from the Sun, Neptune is 30 AU away from the Sun (which that means that Neptune’s distance from the Sun is thirty times the distance between the Earth and the Sun).
THE TELESCOPE SETUP
To see Neptune the closest, I chose the 10mm eyepiece to increase the power. In my case, I again used my small traveling telescope which is a Celestron Travel Scope 70.
I then queried the SkyGuide app (that I’ve used for the past 2 years) to see when and where Neptune would rise during the evening hours. On October 22, it was positioned near constellation Aquarius. Everything was ready once again . . .
GETTING A CLEAR VIEW
Around 9:30 PM Arizona time, I took a look. With the telescope, I could very faintly see Neptune as a lightly tinged bluish and light green “star” among the others. As I’m in the a Phoenix metro area, the telescope helped.
The upper left shows a slightly sharper/larger image to what I saw, but the iPhone I had was not able to zoom in clearly through the scope lens. It was more blurred given atmospheric conditions like temperature, humidity, faint clouds, etc but I could clearly make out the striking methane blue atmosheric hue. I’ve lately been looking into scope options. 🔭💫
As before, a small telescope similar or larger is needed to see Neptune, best at opposition where Earth and Neptune are closest. It could be used or go down to an observatory that might be close to you.
For The Great Galactic Space Gimmick, I’m Gimmick Commander Ben Faltinowski. 🔭 ⭐️
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