Makemake

Makemake

Makemake is one of the most fascinating and remote worlds in the Solar System. Officially designated 136472 Makemake, it is a dwarf planet located in the Kuiper Belt, the vast region populated by icy bodies that extends beyond the orbit of Neptune.
Discovered on March 31, 2005, by a team of astronomers led by Michael E. Brown at the Palomar Observatory, Makemake is one of the largest known trans-Neptunian objects. Its discovery, along with that of other large icy bodies, contributed to the debate that led the International Astronomical Union to redefine the concept of a planet in 2006, officially introducing the category of dwarf planets.
Its name derives from Easter Island mythology: Makemake is, in fact, the deity of creation in the tradition of the Rapa Nui people. The choice was no coincidence, as the object was discovered just days after the Easter holiday.

Astronomical observation –
Makemake orbits the Sun at an average distance of about 45 astronomical units, or over 6.5 billion kilometers. Its orbit is moderately elliptical and highly inclined to the ecliptic plane: with an inclination of about 29°, the dwarf planet spends much of its time far from the regions of the sky most frequently monitored by astronomers. This characteristic explains why, despite its remarkable brightness, it was discovered relatively late.
It completes one orbit in just over 300 years. It is currently near aphelion, the farthest point from the Sun, which it will reach around 2033. Its trajectory places it among the classic Kuiper Belt objects, in the so-called “dynamically hot” population, composed of bodies with inclined orbits and relatively stable over time.
Observed from Earth, Makemake appears as a simple point of light, indistinguishable from a star. Even the most powerful telescopes cannot resolve its disk. Information about its shape and size comes mainly from indirect observations, such as the 2011 stellar occultation, during which the dwarf planet temporarily obscured a distant star, allowing astronomers to precisely measure its profile.
Important contributions to the study of Makemake have come from space telescopes such as the Hubble Space Telescope and the James Webb Space Telescope, which analyzed the dwarf planet’s reflected light and infrared spectrum, revealing its chemical composition.

Physical Characteristics –
With a mean diameter of approximately 1,430 kilometers, Makemake is the fourth-largest dwarf planet known, after Pluto, Eris, and Haumea. Observations indicate that it has a slightly flattened shape at the poles, consistent with a state of hydrostatic equilibrium: its own gravity has molded it into a nearly spherical shape.
Its density suggests a mixed composition of rock and water ice. Its interior is likely differentiated, with a rocky core surrounded by layers of ice. Some studies even suggest the possible presence of a subsurface ocean, kept liquid by the residual heat of its formation and the decay of radioactive elements.
Makemake’s surface is extremely cold: temperatures range between 30 and 40 kelvins, or about –240°C. Under these conditions, substances such as methane can exist as solid ice. Methane ice is the dominant component of its surface, accompanied by small amounts of ethane, acetylene, and other hydrocarbons.
Ultraviolet radiation and cosmic rays slowly transform methane into complex organic compounds called tholines, which are responsible for the observed reddish color. Despite this, Makemake appears very bright: it reflects about 80% of the incident sunlight, a sign of a surface covered in relatively “fresh” ice.
A particularly interesting aspect concerns possible geological activity. Recent data suggest the presence of gaseous methane, which could indicate active outgassing or a tenuous, transitory atmosphere. Furthermore, an anomalous mid-infrared emission has been interpreted as a possible signal of a cryovolcanic hotspot, a region where icy materials could emerge from the interior in the form of “cold lava.”
Makemake also has a natural satellite, designated S/2015 (136472) 1, discovered in 2015 by the Hubble Space Telescope. This small moon, likely dark and about 175 kilometers in diameter, orbits the dwarf planet in about 18 days. Its discovery has allowed a more precise estimate of Makemake’s mass.

Space Missions –
Makemake has never been visited by a space probe. Everything we know about it comes from remote observations. However, scientific interest in it is considerable. The possibility of it harboring a subsurface ocean, combined with signs of geological activity and its unique surface composition, makes it a very attractive target for future missions.
Preliminary studies have shown that a flyby mission could reach it in approximately 10 to 20 years, taking advantage of gravitational pull from Jupiter or Saturn. Direct exploration would allow us to better understand not only Makemake, but also the origin and evolution of icy dwarf planets and, more generally, the primitive bodies that testify to the early history of the Solar System.
Makemake thus remains a distant and mysterious world: a small dwarf planet at the edge of the Solar System that continues to provide precious clues to its most ancient origins.

Guido Bissanti