Moons of Haumea

A small world has two moons.

Scientists found them in 2005.

Long ago, something hit the small world. This hit broke off pieces of ice. These pieces became the two moons.

The big moon is very bright. It is covered in pure ice. The smaller moon is much lighter. It moves in a strange way.

The big moon stays in a steady path. The small moon has a bumpy path. This happens because the big moon pulls on it.

These moons are far away in space. They are special parts of their home.

A dwarf planet named Haumea has two moons.

Scientists found them in 2005 using large telescopes. The moons are named Hiiaka and Namaka. They are named after daughters of a Hawaiian goddess.

These moons are very special. They were likely made from Haumea itself. Long ago, a huge object hit Haumea. This hit broke off pieces of icy material. These pieces became the moons.

This is why the moons look like Haumea. They both have lots of water ice.

Hiiaka is the larger, outer moon. It is about 310 km wide. It orbits Haumea every 49 days. Namaka is the smaller, inner moon. It is about 170 km wide. Namaka has a strange, bumpy path. This is called an eccentric orbit. This happens because the big moon pulls on it. The shape of Haumea also pulls on it.

Scientists think there may be even smaller moons. But they have not found any yet.

The dwarf planet Haumea has two small moons.

These moons are named Hiiaka and Namaka. They are very special because they belong to a collisional family. This means they were likely born from a huge impact. Long ago, a large object hit Haumea. This hit blasted off parts of its icy mantle. The broken pieces of ice stayed near Haumea. These pieces eventually became the two moons we see today.

These moons work in a very interesting way. Hiiaka is the larger moon on the outside. It is about 310 km wide. It orbits Haumea in a nearly circular path every 49 days. Namaka is the smaller moon on the inside. It is about 170 km wide. Namaka has a mass only one tenth of Hiiaka. Its orbit is very eccentric, which means it is not a perfect circle. This happens because the shape of Haumea and the pull of Hiiaka affect it.

A team from Caltech discovered these moons in 2005. They used the large telescopes at the W. M. Keck Observatory in Hawaii. They first found the outer moon, Hiiaka, on 26 January 2005. They nicknamed it "Rudolph" at first. They found the inner moon, Namaka, on 30 June 2005. They nicknamed it "Blitzen." On 17 September 2008, the International Astronomical Union gave them their permanent names. These names come from the daughters of the Hawaiian goddess Haumea.

There are many specific facts about these moons. Hiiaka is covered in nearly pure crystalline water ice. This is rare for objects in the Kuiper belt. Namaka orbits Haumea every 18 days. Its orbit is also tilted at an angle of 13 degrees. On 19 June 2009, an observatory in Brazil saw Namaka pass in front of Haumea. This event is called an occultation. Scientists use these moments to learn about the size and shape of these distant worlds.

Learning about these moons helps us understand our solar system. They are like pieces of a broken puzzle. The moons and the dwarf planet share the same surface material. This shows that they all came from the same original body. It is like if you dropped a glass bowl and the pieces stayed together. The moons are small fragments of the larger world. Even though they are far away, they tell a big story about what happened billions of years ago.

The dwarf planet Haumea is orbited by two small, fascinating moons. These satellites are named Hiiaka and Namaka. They are unique because they are part of an extended collisional family. This means they were likely created by a massive impact long ago.

This collision likely disrupted Haumea's icy mantle. The resulting icy debris eventually formed these two moons. Understanding these moons helps scientists reconstruct the violent history of the Kuiper belt.

The formation of these moons involves a complex process of destruction and regrowth. Scientists believe a large impact occurred billions of years ago. This impact blasted off much of Haumea's original icy mantle. Most of the dwarf planet is now composed of rock. The remaining ice exists only as a superficial layer. The fragments of that shattered ice became small Kuiper belt objects. These pieces, including Hiiaka and Namaka, stayed near Haumea.

This makes the moons fragments of the original body rather than captured objects.

Hiiaka is the larger and outermost moon of the system. It has a mean diameter of approximately 310 km. This size is about 0.5% of Haumea's size. Hiiaka orbits Haumea in a nearly circular path every 49 days. Its surface is covered in nearly pure crystalline water ice. This is a rare finding among objects in the Kuiper belt. The presence of this ice was confirmed through infrared spectroscopy.

The strong absorption features at 1.5, 1.65, and 2 μm indicate this specific composition.

Namaka is the smaller, inner moon of the system. It has a mass that is only one-tenth that of Hiiaka. Based on its mass, its diameter is estimated to be about 170 km. Namaka orbits Haumea every 18 days. Its orbit is quite different from Hiiaka's because it is moderately elliptical. This means it follows an eccentric path rather than a perfect circle. As of 2008, its orbit was also inclined by 13 degrees relative to Hiiaka. This inclination causes constant perturbations in its movement.

The history of these discoveries began in 2005. A team from Caltech used the W. M. Keck Observatory in Hawaii to find them. They first identified the outer moon, Hiiaka, on 26 January 2005. The team originally nicknamed this moon "Rudolph." They discovered the inner moon, Namaka, on 30 June 2005. They nicknamed this second moon "Blitzen." On 17 September 2008, the International Astronomical Union announced their official names. These names honor the daughters of the Hawaiian goddess Haumea.

The orbital dynamics of Namaka are especially complex due to gravitational forces. Namaka's orbit is influenced by the elongated shape of Haumea. It is also heavily influenced by the much larger Hiiaka. The two moons appear to be close to an 8:3 orbital resonance. This resonance strongly perturbs Namaka's path. It causes the argument of periapsis to precess at about −6.5 degrees per year. This precession has a period of 55 years.

Such interactions are common in systems where moons are moving outward due to tidal dissipation.

Observing these moons requires powerful technology. The moons are too faint for telescopes smaller than 2 meters. However, Haumea itself is the third-brightest object in the Kuiper belt. It has a visual magnitude of 17.5. This makes Haumea easy to see with large amateur telescopes. Scientists used the Hubble Space Telescope to separate the moons' light from Haumea. They also used the Spitzer Space Telescope to measure Haumea's albedo. This helped them calculate the estimated sizes of the moons.

One rare event used to study these bodies is an occultation. This happens when a moon passes in front of the dwarf planet. From 2008 to 2011, the orbits appeared edge-on from Earth. This allowed Namaka to periodically occult Haumea. On 19 June 2009, an occultation was observed from Brazil. These transits provide precise data about the size and shape of the objects. Because Namaka's orbit is being torqued by Hiiaka, these viewing angles can last for several years. This provides a unique window into the mechanics of the outer solar system.