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Jupiter Nomenclature

The above sketch made October 13, 1999.

Here is a link of all of my Jupiter drawings and observing reports on my web site.

In the late 1930's, three white ovals formed in Jupiter's South Temperate Belt (STB) and were designated as FA, BC and DE. Ovals BC and DE merged in 1998 formed the oval BE. The above sketch of Jupiter made on October 13, 1999 shows ovals BE and FA. These two ovals merged in March 2000 and formed oval BA.

Since 2000 BA has remained white in color, but at the end of 2005 oval BA began to change to a brown color, and on February 24, 2006 Filipino amateur astronomer Christopher Go noted that its color changed to that of the Great Red Spot. Dr. Tony Phillips gave it the name "Red Spot Jr." or "Red Jr." although professional astronomers still refer to it as oval BA.

The above sketch made December 23, 2001. Note that since the first sketch was made in October 1999 SEB has undergone considerable changes, fading from brown to grey, and becoming bisected by a rift.

October 17, 1987, 0:15 - 0:40 UT, seeing 3 - 4 (0 worst, 5 best), transparency 5. System I Central Meridian 260.7, System II Central Meridian 62.6.

The above sketch made September 28, 1987
SPR - South Polar Region
SSSTZ - South South South Temperate Zone
SSSTB - South South South Temperate Belt
SSTZ - South South Temperate Zone
SSTB - South South Temperate Belt
STZ - South Temperate Zone
STB - South Temperate Belt
DE - white oval DE
STrZ - South Tropical Zone
SEBs - The South Equatorial Belt south
SEBz - The South Equatorial Belt zone
SEBn - South Equatorial Belt north
NEB - North Equatorial Belt
NTrZ - NTrZ - North Tropical Zone
NTB - North Temperate Belt
NTZ - North Temperate Zone
NPR - North Polar Region
The above sketch made October 19, 1987
SPR - South Polar Region
SSSTZ - South South Temperate Zone
SSSTB - South South Temperate Belt
SSTZ - South Temperate Zone
SSTB - South Temperate Belt
BC - white oval BC
STrZ - South Tropical Zone
SEB - The South Equatorial Belt
GRS - Great Red Spot
NEB - North Equatorial Belt
NTrZ - NTrZ - North Tropical Zone
NTB - North Temperate Belt
NTZ - North Temperate Zone
NNNTB - North North North Temperate Belt
NNNTZ - North North North Temperate Zone
NPR - North Polar Region

This graphic was created by a Curt Renz and used with his permission.

Features in Jupiter's Atmosphere

Bay - a large semi-oval indentation in the edge of a belt. Common along the northern and southern edge of the NEB, as well as along the southern edge of the SEB. Small bays are known as Notches. The Red Spot Hollow (RSH) would be an example of a large bay.

Central Meridian (CM) - the central meridian is an imaginary line through the center of the disk from the south pole to the north pole, dividing the disk into equal halves, independent of phase. By noting the time a feature transits the CM, it is possible to determine the period of rotation of surface or atmospheric features. See Following and Preceding.

Condensation - a small round or somewhat elongated dark spot usually found in belts. If they are very elongated they are called Rods or Bars. Rods or bars (sometimes appearing red in color) are very common along the northern edge of, and embedded in, the NEB, and are occasionally seen in the north temperate latitudes of Jupiter. Bars or rods are sometimes called barges.

Festoons - a dark feature that extends across a zone and connects two belts, such as the NEB to EB. If festoon loops into zone and reconnects to the same belt it started from it is sometimes called a Loop Festoon or Garland. Color of festoons is blue or gray. If festoon does not connect to a belt it is called a Hook. Diffuse, broad vertical festoons are known as Columns. Festoons are often seen in EZ and along the southern edge of NEB.

Following and Preceding - when observing Jupiter with a telescope with an even number of reflections, such as a Newtonian reflector, or refractor used without a star diagonal, south is at the top. Features on the disk appear to rotate from the right hand side to the left hand side of the disk (when using a telescope of different configuration, note that north may be at the top, and the planet may appear to rotate from left to right).

The right hand side of the disk (as defined by the Central Meridian or CM) is the following side of the disk; the left hand side is the preceding side. Using an accurate watch, pencil, and notepad it is possible to make CM timings. When a feature, such as the GRS, approaches the CM, note the time to the nearest minute the time its preceding edge transits the CM. Do the same for its center and following edge.

In our example of the GRS, the notation would read GRSp, GRSc, GRSf, which translates to GRS preceding, GRS center, GRS following. As shorthand notation for other dark or light features, you can use the letter D to indicate a dark feature, W to indicate a white feature. These timings will give you an estimate of when the feature transited the CM. Since features in Jupiter's atmosphere tend to drift over time, these timings will give an estimate of its drift rate relative to other features.

Gap - a wide break in a belt that divides the belt into two or more sections.

Knots - darker, thicker sections of a belt.

Nodule - the opposite of a Condensation, these are small, round bright spots. Seen in NEB, SEB, and Polar Regions.

Ovals - light colored areas, round or oval in shape, that are medium to large in size. Can appear both in dark belts and light zones. Very common in the EZ. Small ovals are known as White Spots. The Great Red Spot (GRS) is an example of a very large oval.

Patch - a large, irregular shaped whitish colored area, seen in the EZ and the polar regions.

Projection - a dark prominence on the edge of a belt.

Rift - a long, thin bright streak that extends horizontally along the interior of a belt.

Streak - an elongated Nodule.

Veil or Shading - the opposite of Patch, these are large, uniform dusky areas sometimes seen in zones or polar areas. The EZ near opposition sometimes has a veil or shaded appearance to it.

Jupiter's Atmosphere including Belts and Zones

Jupiter's atmosphere is thought to be composed mostly of hydrogen and helium, with traces of ammonia, phosphine, water vapor, and hydrocarbons. The light colored zones, and dark colored belts, seen in Jupiter's atmosphere are caused by differences in chemical composition and temperature. The colors of the zones and belts give an idea as to their altitude: reds are the highest, then whites and browns, followed by blue as the lowest.

Jupiter's alternating bright zones and dark belts are designated in order from the pole to the equator as: polar, temperate, tropical, and equatorial. Below is a list of each of the belts and zones, its abbreviation, and the system it resides in. Note that belts and zones can sometimes have a north, center, and south component to them, and not all belts and zones are visible during each opposition.

Name of Belt or Zone Abbreviation System*
South Polar Region SPR III**
South South Temperate Zone SSTZ II
South South Temperate Belt SSTB II
South Temperate Zone STZ II
South Temperate Belt STB II
South Tropical Zone STropZ II
South Equatorial Belt, south SEBs II
South Equatorial Belt, center SEBc II
South Equatorial Belt, north SEBn I
Equatorial Zone EZ I
Equatorial Band EB I
North Equatorial Belt, south NEBs I
North Equatorial Belt, center NEBc II
North Equatorial Belt, north NEBn II
North Tropical Zone NTropZ II
North Temperate Belt NTB II
North Temperate Zone NTZ II
North North Temperate Belt NNTB II
North North Temperate Zone NNTZ II
North Polar Region NPR III**

*Since Jupiter does not rotate on its axis at a uniform rate, two rotation periods have been assigned to it: System I is 9 hours 50 minutes and 30 seconds, encompassing the Equatorial Zone, which extends from the northern edge of the South Equatorial Belt to the southern edge of the North Equatorial Belt. All other Jovian latitudes, except for the polar regions, have been assigned a rotation period of 9 hours 55 minutes and 40 seconds, which is System II.

**System III is sometimes used to define the polar regions, or alternately is used by radio astronomers to study Jupiter's rotation. For amateur observations only System I and II are used.

Moons of Jupiter

As of March 1012 Jupiter has 63 moons. This includes the Galilean moons that were discovered independently in 1610 by Galileo Galilei and Simon Marius. Although they are known as the Galilean moons it was Marius who gave them their names: Io (pronounced "EYE oh" or "EE oh", magnitude 4.9), Europa (pronounced "yoo ROH puh", magnitude 5.2), Ganymede (pronounced "GAN uh meed", magnitude 4.5), and Callisto (pronounced "ka LIS toh", magnitude 5.5).

The Galilean moons are easily visible in amateur sized telescopes, and I have seen them in a pair of Oberwerk 11x70mm Binoculars. Also I have been able to resolve the moons as disks using a telescope and based on their size and color I was able to identify them.

Io (Jupiter I) is composed of molten silicate rock, and it may have an iron core. Its surface is covered with volcanic calderas, active volcanoes, lava flows, and lakes of molten sulfur. The mechanism for generating these volcanoes is caused by tidal interactions between Io, Europa, Ganymede and Jupiter. Io may have its own magnetic field.

Europa (Jupiter II) is slightly smaller than the Earth's Moon and is the fourth largest of Jupiter's satellites. Like Io it is composed of molten silicate rock, and may have a small metallic core. It has a weak magnetic field. The surface of Europa has a thin outer layer of ice, which is very smooth and crisscrossed by a series of dark streaks. The surface appears to be very young as there are few craters on it. It is possible that beneath the surface ice there is a layer of liquid water (perhaps a salty ocean) kept liquid by tidally generated heat. If so, it would be the only other place in the solar system other than Earth where liquid water exists in significant quantities.

Ganymede (Jupiter III) is the largest moon in the solar system and is larger then the planet Mercury. Ganymede may have its own magnetic field. It is the largest of Jupiter's known satellites, and it is the largest satellite in the solar system. It has a small molten iron or iron/sulfur core surrounded by a rocky silicate mantle with an icy shell on top. Ganymede has a magnetosphere field that is embedded inside Jupiter's larger magnetic field.

Callisto (Jupiter IV) is only slightly smaller than Mercury. It has a very tenuous atmosphere composed of carbon dioxide, and a weak magnetic field, which may indicate some sort of salty fluid below the surface. Callisto is about 40% ice and 60% rock/iron, and is probably similar to Saturn's moon Titan and Neptune's moon Triton. Callisto's surface is very old and covered with craters like the highlands of Mars and the Moon. This includes a long series of impact craters in a straight line which may have been caused by an object that was tidally disrupted as it passed close to Jupiter (as happened when Comet P/Shoemaker-Levy 9 fragments impacted Jupiter in July 1994) and then impacted on Callisto.

Article 2000 - 2015, Eric Jamison, All rights reserved.

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