Mysterious dwarf planet contains many surprises
There is a mysterious object that orbits our Sun way beyond the orbit of the most distant planet Neptune.
This far out in the solar system the Sun is a feeble dot of light. Out here it is dark, lonely and foreboding.
The mysterious object, only discovered in 2004, is the dwarf planet Haumea, named after a Hawaiian goddess. A dwarf planet that orbits beyond Neptune is called a Trans-Neptunian Object (TNO).
Haumea is the third-largest known TNO after the dwarf planets Eris, discovered in 2005, and Pluto, discovered in 1930.
Eris and Pluto are four and three times more massive than Haumea respectively. The Earth is
500 times more massive than Pluto and 1500 times more massive than Haumea.
Haumea is like no other object in the solar system, a spinning, eggshaped rock 2100km by 1700km by
1150km.
The average distance from the Earth to the Sun is called one Astronomical Unit (AU), about 150 million kilometres. Haumea has an elliptical orbit which is closest to the Sun at 35AU and furthest at 52AU.
In comparison, Neptune’s orbit is on average 30AU.
If you wanted to contact someone on Haumea from Earth it would take about 14 hours, depending on where it is in its orbit relative to Earth, before you received a radio signal reply to your ‘‘hello’’.
The Earth takes one year to complete an orbit of the Sun, whereas it takes 284 Earth years for Haumea to make one orbit of the Sun.
A planet is defined as an object that is gravitationally dominant in its orbital zone and ‘‘clears out the neighbourhood around its orbit’’, meaning that in its orbital zone there are no other objects of comparable size (other than its moons).
A dwarf planet is not large enough to clear its orbital zone.
Haumea is thought to be part of a collisional family, the result of a violent and destructive collision which produced Haumea as well as several other TNOs.
Haumea is the fastest rotating object of more than 100km diameter in the solar system.
It takes this 2100 km-long ellipsoid only 3.9 hours to rotate once on what is the shortest of its axes; this high rotation speed is believed to be the reason for the dwarf planet’s ellipsoidal shape, pulling and stretching its constituent rocks apart along its longest axis. Its speed of rotation means that a single day on Haumea is only 3.9 hours.
The dwarf planet even has two small moons, Hi’iaka and Namaka, also named after Hawaiian goddesses.
The moons are the result of the same collision event that produced Haumea.
Hi’iaka has a diameter of 300km, takes 49 days to complete one orbit of Haumea and has an orbit radius of 50,000km.
Namaka is 170km in diameter, and takes 18 days to complete an orbit at an average distance of
26,000km.
Haumea has more surprises; it has a ring and a very strange surface composition.
The ring which has a radius of
2300km and is 70km across, comprises dust and rock debris. It is the remains of a rock that orbited close enough to the Haumea for the gravitational tug on it exerted by Haumea to be greater than the force binding the constituents of the rock.
The result was that the rock disintegrated and gradually the pieces have distributed themselves in a ring around the dwarf planet.
The surface composition of Haumea is a surprise because it contains regions of crystalline water ice.
The surface temperature is minus 223 degrees Centigrade and at this extreme temperature, water ice should not be a well-ordered crystalline structure but should lack any long-range structure. It should be a chaotic solid mass of molecules referred to as amorphous ice. How it can have retained its crystalline structure is a mystery.
Given a launch date of 2026 it would take a probe over 16 years to reach Haumea.
If such a mission were to be approved, it would hopefully help solve some of the mysteries of this strange world and provide some thought-provoking and humbling pictures of the Sun and Earth seen from a spinning rocky outcrop 8 billion kilometres into space. Most of the original streets in Inglewood were named after prominent Taranaki people of the
19th century. One such man was Henry Robert Richmond.
Born and educated in London, Richmond travelled to New Zealand in 1851. His early years were involved in politics, culminating in his 1865 election to lead the Taranaki Provincial Council. At the time these were the local government bodies responsible for public facilities. They were short-lived political bodies however. So, at the age of 40, Richmond went to Nelson and studied law, qualified as a solicitor and returned to New Plymouth in
1875. He worked in the profession until his untimely death, aged only
61, on a visit to Christchurch in
1890.
Richmond St has seen much change since Henry Richmond’s day. The northern end remains residential, a mix of original and newer houses. Early surveyors’ plans indicate significant commercial redevelopment was undertaken around the Rata Street intersection in the mid-1920s.
Some of the buildings in that area of the town still reflect those years of Inglewood’s development.
Roger Hanson
Contributed by the Taranaki Research Centre I Te Pua Wa¯ nanga o Taranaki at Puke Ariki.