Neptune, the Mystic Trivia Quiz

Answer: Pisces

Neptune is considered the planet of dreams, intuition, and spirituality, which fits well with the 12th and final sign of the zodiac, Pisces, which is deeply associated with themes of:

- Spirituality and mysticism
- Dreams and intuition
- Compassion and empathy
- Creativity and imagination
- Escapism and illusion

As one of the three water signs (along with Cancer and Scorpio), it seems highly apropos that Pisces would be connected with Neptune, named for the Roman god of the sea.

Before Neptune was discovered in 1846, the traditional ruler of Pisces was Jupiter.

Answer: Galileo Galilei

Galileo Galilei had a little bad luck when he first observed Neptune in December of 1612, thinking it was a star... it was stationary in the sky because it had just turned retrograde that very day. Even so, Galileo was an observant scientist, and later observations were noted in his writings (discovered in 2009) where he noted that the star he had found was no longer where he expected it. Even so, no other evidence has been found to indicate that he pursued the matter any further, nor officially thought it anything other than a star.

After Neptune was discovered through mathematical calculation in 1846, other records of the planet's observation over the years were found, including a 1795 record of an errant star by scientists at the Paris Observatory, and again in 1830 by John Herschel, who also thought it a star.

Answer: Urbain Le Verrier

After the discovery of Uranus by William Herschel in 1781, various irregularities were observed in its orbit that could not be explained by Newton's laws of motion and gravitation. In 1821, French astronomer Alexis Bouvard published astronomical tables of that orbit to that point, predicting future positions. When subsequent observations that ended up not quite fitting the model, Bouvard surmised a number of theories as to why, including the potential presence of another planet.

In the mid-1840s, two scientists - independent of one another - began mathematical calculations on the position and mass of such a planet, to explain its effects on Uranus: John Couch Adams at Cambridge, and Urbain Joseph Le Verrier in Paris. Le Verrier sent his predictions to Johann Gottfried Galle at the Berlin Observatory, who found Neptune within one degree of Le Verrier's prediction on his first night of searching on September 23-24, 1846.

Retrospectively, John Couch Adams' calculations were nearly as accurate as Le Verriers, with Neptune discovered within 12 degrees of Adams' prediction.

Answer: Ice giant

The four planetary giants in our Solar System are divided into two gas giants (Jupiter and Saturn) and two ice giants (Uranus and Neptune). While at first glance, they may seem similar, there are key differences in their composition. With Voyager 2's flyby in 1989, scientists were finally able to see how the two outer planets differed from the closer gas giants, and updated the terminology for the rest of us, accordingly.

Gas giants are primarily composed of the 'lighter' elements, such as hydrogen and helium, and have no solid surface. Although they do possess solid or rocky cores, most of their mass is made up of gases that, under extreme pressure within their interiors, are compressed into liquid form.

Ice giants, on the other hand, are composed mainly of elements heavier than hydrogen and helium, such as water, methane, and ammonia, making up a higher percentage of mass. And while the term 'ice' is used, the internal components of ice giants are not solid ice but rather hot, dense fluids, or supercritical fluids, under immense pressure.

Answer: Methane

While Neptune's atmosphere (as opposed to its core) is mostly hydrogen and helium, the presence of methane, which absorbs red light and reflects blue light, is what gives the planet its distinctive blue hue.

Methane's chemical formula is CH4 (visual clue), while the erroneous choices were:
Ammonia - NH3
Ethane - C2H6
Propane - C3H8

Interestingly, the earliest close-up photographs of Neptune by Voyager 2 showed it to be a much darker shade of blue than it actually is. This was because of the image processing done at the time, deliberately enhancing the images to make specific atmospheric features, like clouds and storms, more visible.

The lighter blue photos included in this quiz were adjusted by NASA engineers to more accurately reflect Neptune's colours.

Answer: 57

As noted in the question, Neptune is about four times wider than Earth. To put that in a more 'down-to-earth' frame of reference, if Earth were the size of a nickel, Neptune would be about as big as a baseball.

As for the volume of Neptune compared to Earth (more pertinent for being able to answer the question), Neptune is approximately 57.7 times the volume of Earth, so it could comfortably hold 57 Earths, but not quite 58.

More specifically, the volume of Neptune is approximately 6.254 x 10^13 km3 (1.50 x 10^13 cu mi), while Earth's volume is around 1.083 x 10^12 km3 (2.60 x 10^11 cu mi).

Answer: 2011

As noted in the question, one day on Neptune takes about 16 hours (the time it takes for Neptune to rotate or spin once). And Neptune makes a complete orbit around the Sun (a year in Neptunian time) in about 165 Earth years, or more precisely, 60,190 Earth days.

So, after the official discovery of Neptune on September 23 in 1846, the planet completed its first Neptunian year on July 12, 2011. And on July 8, 2011, the final space shuttle flight (STS-135) was launched, landing on July 21 (the program began in 1972).

As the furthest planet from the Sun, is it any wonder a Neptunian year is so long? From an average distance of 4.5 billion km (2.8 billion mi), Neptune is 30 astronomical units away from the Sun (one astronomical unit (abbreviated as AU), is the distance from the Sun to Earth). From this distance, it takes sunlight 4 hours to travel from the Sun to Neptune.

Answer: True

Neptune is our Solar System's windiest world. Despite its great distance and low energy input from the Sun, Neptune's winds can be three times stronger than Jupiter's and nine times stronger than Earth's. These winds whip clouds of frozen methane across the planet at speeds of more than 2,000 km/h (1,200 mph). Even Earth's most powerful winds hit only about 400 km/h (250 mph).

Answer: Voyager 2

Voyager 2 was launched on August 20, 1977 on a 'Grand Tour' that took it past Jupiter in 1979, Saturn in 1981, Uranus in 1986, and finally Neptune in 1989. Even though the existence of rings around Neptune had been suggested and possibly observed (through occlusions), it was not until Voyager 2 made its flyby that this was confirmed.

Neptune has at least five main rings and four prominent ring arcs that have been observed. Starting near the planet and moving outward, the main rings are named Galle, Le Verrier, Lassell, Arago, and Adams, after all the scientists who had a part in various Neptunian discoveries. Four of these names appear in other questions in this quiz, and the fifth - François Arago, director of the Paris Observatory - was instrumental in prompting Le Verrier to begin his mathematical discovery of the planet.

The other devices could not have photographed Neptune in 1979:

Voyager 1 was launched on September 5, 1977 and made flybys of Jupiter in 1979 and Saturn in 1980, before being directed to depart the Solar System.

The Hubble Space Telescope was launched in 1990, after delays due to the Challenger disaster of 1986).

And even though the photograph accompanying this question was taken by the James Webb Space Telescope, that device did not come into service until 2021.

Answer: It has a retrograde orbit

Neptune's 16th known moon was discovered in 2021, and in alignment with the mythology surrounding Neptune, the moons are named for various lesser sea gods and nymphs.

Due to the oddity of Triton having a retrograde orbit (it revolves around Neptune in the opposite direction from the planet's direction of rotation), scientists believe that it was originally a dwarf planet within the Kuiper belt that was captured by Neptune's gravity.

While Triton has no active volcanoes, Voyager 2 did capture images of a couple of geysers spewing icy materials into the moon's thin atmosphere as it flew past.

Triton is not the fastest moon in the Solar System; that honour goes to Metis, an inner moon of Jupiter. Nor is it the largest moon, a status claimed by another moon of Jupiter: Ganymede. That said, Triton is still quite large, ranking 7th among the largest moons in our Solar System.