The first detailed images beamed back by NASA’s New Horizons spacecraft after its flyby of Ultima Thule show that the icy ‘worldlet’ resembles a reddish snowman.

About Ultima Thule

  • It is the most distant and possibly the oldest space object ever explored.
  • It has been renamed by International Astronomical Union(IAU) as Arrokoth’
  • It is one of many frigid bodies way out in the Kuiper Belt, the solar system's "third zone" beyond Neptune's orbit. 
  • It belongs to a class of Kuiper belt objects called the “cold classicals”, which have nearly circular orbits with low inclinations to the solar plane.


The Kuiper belt 

  • It is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune to approximately 50 AU from the Sun.
  • It consists mainly of small bodies or remnants from when the Solar System formed.
  • While many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia and water. 
  • The Kuiper belt is home to three officially recognized dwarf planets: Pluto, Haumea and Makemake. 


  • It used to be 2 separate objects. It likely formed over time as a rotating cloud of small, icy bodies started to combine. 
  • Eventually, 2 larger bodies remained & slowly spiraled closer until they touched, forming the current bi-lobed object.


NASA's New Frontiers program

  • The New Frontiers program is a series of space exploration missions being conducted by NASA with the purpose of researching several of the Solar System bodies, including the dwarf planet Pluto.
  • Missions under the program are as follows

New Horizons




It's the first Mission to the Pluto System and the Kuiper Belt.


It was launched in 2006 and reached Pluto in 2015

It is a space probe orbiting the planet Jupiter


It was launched in 2011 and entered Jupiter orbit in 2016

It will travel to a near-Earth asteroid named Bennu and bring a small sample back to Earth for study.


It was launched in September 2016

It is a planned spacecraft. It will send a mobile robotic rotorcraft lander to Titan, the largest moon of Saturn.


International Astronomical Union (IAU)

  • It was founded in 1919. 
  • Its individual members are professional astronomers from all over the world, at the Ph.D. level and beyond, who are active in professional research, education and outreach in astronomy. 
  • Its mission is to promote and safeguard the science of astronomy in all its aspects, including research, communication, education and development, through international cooperation.
  • The IAU is a member of the International Science Council (ISC).
    • The International Science Council (ISC) is a non-governmental organization with a unique global membership that brings together international scientific unions and associations and national and regional scientific organizations including Academies and Research Councils.
  • Activities of the IAU are as follows
    • The organization of scientific meetings.
    • Providing definition of fundamental astronomical and physical constants; unambiguous astronomical nomenclature 
    • Holding informal discussions on the possibilities for future international large-scale facilities.