Constellations: Microscopium 'the Microscope' Content from the guide to life, the universe and everything

Constellations: Microscopium 'the Microscope'

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The shield of the Science, Mathematics and Engineering faculty of the h2g2 University.Constellations: Overview | Andromeda | Antlia | Apus | Aquarius | Aquila | Ara | Aries | Auriga | Boötes | Caelum
Camelopardalis | Cancer | Canes Venatici | Canis Major | Canis Minor | Capricornus | Carina | Cassiopeia | Centaurus
Cepheus | Cetus | Chamæleon | Circinus | Columba | Coma Berenices | Corona Australis | Corona Borealis | Corvus
Crater | Crux | Cygnus | Delphinus | Dorado | Draco | Equuleus | Eridanus | Fornax | Gemini | Grus | Hercules | Horologium
Hydra | Hydrus | Indus | Lacerta | Leo | Leo Minor | Lepus | Libra | Lupus | Lynx | Lyra | Mensa | Microscopium | Monoceros
Musca | Norma | Octans | Ophiuchus | Orion | Pavo | Pegasus | Perseus | Phoenix | Pictor | Pisces | Piscis Austrinus
Puppis | Pyxis | Reticulum | Sagitta | Sagittarius | Scorpius | Sculptor | Scutum | Serpens | Sextans | Taurus
Telescopium | Triangulum | Triangulum Australe | Tucana | Ursa Major | Ursa Minor | Vela | Virgo | Volans | Vulpecula
Nature composes some of her loveliest poems for the microscope and the telescope.
– Theodore Roszak

Short form:Mic
Area:210 sq deg
Co-ordinates1:21h, −35°

Microscopium, the Microscope is a small southern constellation which is bordered by Capricornus, Sagittarius, Grus, Indus and Piscis Austrinus. It was named after the apparatus invented by Zacharius Janssen in 1590. Microscopes are similar to telescopes in that they are both used by scientists to examine scientific matter. The most common microscope is the 'optical microscope'.


The sky in the Southern Hemisphere where Microscopium resides was not detailed by the ancient Greeks as they felt the area was much too boring. The Graeco-Egyptian astronomer Ptolemy, in the star catalogue in his 150 AD Almagest, lists some stars in this general area of the sky but describes them as 'around Piscis Austrinus outside the constellation'.

In the 18th Century French astronomer Abbé Nicolas Louis de Lacaille (1713 - 1762) made a voyage to the Cape of Good Hope in South Africa. There he named 14 new constellations in the Southern Hemisphere and Microscopium was born. Some constellations that he formed to honour scientific instruments were Telescopium the telescope, Octans the octant, Reticulum the reticle (part of a telescope), Pyxis the mariner's compass and Norma the set square.


Usually, the scientific star names are simple to understand (if you know your Greek alphabet). For example: the 'alpha' star means that it is the brightest star in that constellation. The next brightest is designated 'beta', etc. However, this is not true of the constellation Microscopium.

The Greek letters combined with the genitive of the constellation name are known as the 'Bayer designation' after the man who devised the system. Some stars have proper names as well, for example, alpha Gruis is called Alnair, but none of the stars of Microscopium have a proper name. Other stars are known by their catalogue number. Later discovered variable stars are given upper case English letters, like AX Microscopii.

Stars of Microscopium

AX Microscopii (also known as Lacaille 8760) is a red dwarf flare star considered local due to it being just 12.9 light years2 distant. Flare stars are a special type of red dwarf. They emit flares that are unusual given the size and brightness of the star. The flare stars can erupt at any time and numerous expulsions can be given off from the same star within a matter of hours to days, taking a number of minutes to reach full brightness. Our Sun also gives off solar flares, but they are relatively small in comparison to the amount of energy it produces.

AT Microscopii consists of two variable red dwarfs that make up a binary star system.

AU Microscopii is a variable red dwarf which has a debris disc reaching about 210AU (astronomical units) from the central star - about seven times further from the star than Neptune3 is from the Sun. It is thought that such discs are the early stages in the evolution of a planetary system. The planets in our own Solar System, including the Earth, are believed to have formed from a debris disc. At 17AU radius from the star there is a gap in the disc indicative of an orbiting planet, but it is way beyond the habitable zone.

Star Table

StarDesignationBrightness (mag)Spectral classification
and/or comments
γgamma Mic+4.67 varG6III
εepsilon Mic+4.71 varA1V
θ1theta1 Mic+4.82 varA2p(Cr-Eu-Sr-Mg)
αalpha Mic+4.90 varG7III
νnu Mic+5.11K0III
ιiota Mic+5.11F1IV
ζzeta Mic+5.30 varF3V
ηeta Mic+5.53 varK3III
δdelta Mic+5.68 varK0
θ2theta2 Mic+5.77 varA0IIIpSi
βbeta Mic+6.04A2Vn
AUAU Mic+8.6 var Red dwarf/
has a debris disc
AXAX Mic+8.69 var Red dwarf flare star
ATAT Mic+10.24Binary

Extrasolar Planets in Microscopium

There have been confirmed extrasolar planetary systems found in the constellation Microscopium up to 2017. The orbital period given in the table below is the time the planet takes to orbit its parent star, which we know of as a year. The mass of the extrasolar planet is compared to that of Jupiter, our Solar System's largest planet, known by astronomers as the 'Jovian scale'.

Extrasolar Planets Table

Star name or
catalogue number
catalogue number
Planet mass
(Jovian scale)
Orbital period
(Earth days)
Year of discoveryComments
WASP-7WASP-7 b1.284.952008Hot Jupiter
HIP 105854HIP 105854 b8.21842014Superjovian
WASP-94AWASP-94A b0.453.952014Hot gas giant
WASP-94BWASP-94B b0.6222014Hot gas giant
WASP-92WASP-92 b0.82.172016Hot gas giant
WASP-133WASP-133 b1.162.182016Hot Jupiter


The New General Catalogue (NGC) was compiled by John Louis Emil Dreyer (the director of the Armagh Observatory from 1882 to 1916). This was later expanded to include newer discoveries, and is being continually updated as the NGC/IC Project. There are a number of NGC and IC (Index Catalogue) objects in Microscopium, which are all galaxies.

Of the seven brightest galaxies, four are spirals and three are elliptical. The spirals are catalogued NGC 6925, NGC 6923, NGC 6919 and NGC 6947, and the ellipticals are NGC 6958, NGC 7012 and IC 5105.

1Current IAU guidelines use a plus sign (+) for northern constellations and a minus sign (−) for southern ones.2A light year is the distance light travels in one year, roughly 5.88 trillion miles or 9.46 trillion km.3Neptune is the furthest planet from the Sun since the demotion of Pluto in 2006.

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