3 Juno

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3 Juno

Juno (or as in ), formal designation 3 Juno in the Minor Planet Center catalogue system, was the third asteroid

Asteroid

Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun, smaller than planets but larger than meteoroids....
to be discovered and is one of the larger main belt asteroids, being one of the two largest stony (S-type

S-type asteroid

S-type asteroids are of a silicaceous composition, hence the name. Approximately 17% of asteroids are of this type, making it the second most common after the C-type asteroid....
) asteroids, along with 15 Eunomia

15 Eunomia

'15 Eunomia' is a very large asteroid in the inner asteroid belt. It is the largest of the stony asteroids, and somewhere between the 8th to 12th largest Main Belt asteroid overall ....
. Juno is estimated to contain 1% of the total mass of the asteroid belt. Juno was discovered on September 1, 1804, by German

Germany

Germany , officially the Federal Republic of Germany , is a country in Central Europe. It is bordered to the north by the North Sea, Denmark, and the Baltic Sea; to the east by Poland and the Czech Republic; to the south by Austria and Switzerland; and to the west by France, Luxembourg, Belgium, and the Netherlands....
astronomer

Astronomer

An astronomer is a scientist who studies Celestial body such as planets, stars, and Galaxy.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using physical laws....
Karl L. Harding

Karl Ludwig Harding

Karl Ludwig Harding was a Germany astronomer notable for having discovered the asteroid 3 Juno.Harding was born in Lauenburg. In 1796 Johann Hieronymus Schr?ter hired Harding as a tutor for his son....
and named after the mythological figure Juno

Juno (mythology)

File:Juno sospita pushkin.jpgJuno was an Roman religion, the protector and special counselor of the state. She is a daughter of Saturn and sister of the chief god Jupiter and the mother of Juventas, Mars , and Vulcan ....
, the highest Roman goddess.

is one of the larger asteroids, perhaps tenth by size and containing approximately 1.0% the mass of the entire Main asteroid belt.

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Encyclopedia

Juno (or as in ), formal designation 3 Juno in the Minor Planet Center catalogue system, was the third asteroid

Asteroid

S-type asteroid

15 Eunomia

Germany

Astronomer

Karl Ludwig Harding

Juno (mythology)

Characteristics

Juno is one of the larger asteroids, perhaps tenth by size and containing approximately 1.0% the mass of the entire Main asteroid belt. It is the second most massive S-type asteroid after 15 Eunomia. Though one of the most massive asteroids, Juno has only 3% the mass of Ceres.

Amongst S-type asteroids, Juno is unusually reflective, which may be indicative of distinct surface properties. This high albedo explains its relatively high apparent magnitude

Apparent magnitude

The apparent magnitude of a celestial body is a measurement of its brightness as seen by an observer on Earth, normalized to the value it would have in the absence of the Earth's atmosphere....
for a small object not near the inner edge of the asteroid belt. Juno can reach +7.5 at a favourable opposition, which is brighter than Neptune

NEPTUNE

=Overview=The project, along with sister project, VENUS, offers a unique approach to ocean science. Traditionally, ocean scientists have relied on infrequent ship cruises or space-based satellites to carry out their research....
or Titan

Titan (moon)

Titan or Saturn VI is the largest natural satellite of Saturn, the only moon known to have a dense celestial body atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found....
, and is the reason for it being discovered before the larger asteroids Hygiea

10 Hygiea

'10 Hygiea' is an asteroid located in the main asteroid belt. With somewhat oblong diameters of 350?500 km, and a mass estimated to be 2.9% of the total mass of the belt, it is the List_of_noteworthy_asteroids by volume and mass....
, Europa

52 Europa

52 Europa is one of the larger asteroids. It has a diameter of 300 km, and was discovered on February 4, 1858 by Hermann Mayer Salomon Goldschmidt....
, Davida

511 Davida

511 Davida is a large asteroid belt C-type asteroid. It was discovered by Raymond Smith Dugan in 1903. It is thought to be one of the ten List_of_noteworthy_asteroids#Largest_known_asteroids_.28out_to_the_orbit_of_Jupiters....
, and Interamnia

704 Interamnia

'704 Interamnia' is a very large asteroid, with an estimated diameter of 350 kilometres. Its mean distance from the Sun is 3.067 . It was discovered on October 2, 1910 by Vincenzo Cerulli, and named after the Latin name for Teramo, Italy, where Cerulli worked....
. At most oppositions, however, Juno only reaches a magnitude of around +8.7—only just visible with binoculars

Binoculars

Binocular telescopes, or binoculars , are two identical or mirror-symmetry optical telescopes mounted side-by-side and aligned to point accurately in the same direction, allowing the viewer to use both eyes when viewing distant objects....
—and at smaller elongations a telescope

Telescope

A telescope is an instrument designed for the observation of remote objects by the collection of electromagnetic radiation. The first known practically functioning telescopes were invented in the Netherlands at the beginning of the 17th century....
will be required to resolve it. It is the main body in the Juno family.

Juno was originally considered a planet, along with 1 Ceres, 2 Pallas

2 Pallas

'2 Pallas' is one of the largest asteroids and is located in the main asteroid belt. It was the second asteroid to be discovered, by astronomy Heinrich Wilhelm Matth?us Olbers on March 28, 1802....
, and 4 Vesta

4 Vesta

4 Vesta is the second most massive object in the asteroid belt, with a mean diameter of about 530 km and an estimated mass of 9% of the mass of the entire asteroid belt....
. In 1811, Schröter

Johann Hieronymus Schröter

Johann Hieronymus Schr?ter was a Germans astronomer.Schr?ter was born in Erfurt, and studied law at G?ttingen University from 1762 until 1767, after which he started a ten-year-long legal practice....
estimated Juno to be as large as 2290 km in diameter. All four were re-classified as asteroids as additional asteroids were discovered. Juno's small size and irregular shape preclude it from being a dwarf planet

Dwarf planet

A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be rounded by its own gravity but has not Clearing the neighbourhood of planetesimals and is not a natural satellite....
.

Juno orbits at a slightly closer mean distance to the Sun

Sun

The Sun , a G V star, is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 98.6% of the Solar System's mass....
than Ceres or Pallas. Its orbit is moderately inclined at around 12° to the ecliptic

Ecliptic

The ecliptic is the apparent path that the Sun traces out in the sky during the year. As it appears to move in the sky in relation to the stars, the apparent path aligns with the planets throughout the course of the year....
, but has an extreme eccentricity

Orbital eccentricity

In astrodynamics, under standard assumptions in astrodynamics, any orbit must be of conic section shape. The eccentricity of this conic section, the orbit's eccentricity, is an important parameter of the orbit that defines its absolute shape....
, greater than that of Pluto

Pluto

Pluto , Minor planet names Pluto, is the second-largest known dwarf planet in the Solar System and the tenth-largest body observed directly orbiting the Sun....
. This high eccentricity brings Juno closer to the Sun at perihelion than Vesta and further out at aphelion than Ceres. Juno had the most eccentric orbit of any known body until 33 Polyhymnia

33 Polyhymnia

33 Polyhymnia is a main belt asteroid.It was discovered by Jean Chacornac on October 28, 1854 and named after Polyhymnia, the Greek mythology Muse of sacred hymns....
was discovered in 1854, and of asteroids over 200 km in diameter only 324 Bamberga

324 Bamberga

324 Bamberga is one of the largest asteroid in the Asteroid belt. It was discovered by Johann Palisa on February 25, 1892 in Vienna, making it one of the last large asteroids discovered....
has a more eccentric orbit.

Juno rotates in a prograde

Retrograde and direct motion

Direct motion is the motion of planetary body in a direction similar to that of other bodies within its system, and is sometimes called prograde motion....
direction with an axial tilt

Axial tilt

In astronomy, axial tilt is the inclination angle of a planet axis of rotation in relation to its Orbital plane . It is also called axial inclination or obliquity....
of approximately 50°. The maximum temperature on the surface, directly facing the Sun, was measured at about 293 K

Kelvin

The kelvin is a Units of measurement of temperature and is one of the seven SI base units. The Kelvin scale is a Thermodynamic temperature scale where absolute zero, the theoretical absence of all thermal energy, is zero ....
on October 2, 2001. Taking into account the heliocentric distance at the time, this gives an estimated maximum temperature of 301 K (+28 °C

Celsius

Celsius is a temperature scale that is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death....
) at perihelion.

Spectroscopic studies of the Junonian surface permit the conclusion that Juno could be the progenitor of chondrite

Chondrite

Chondrites are stony meteorites that have not been modified due to melting or differentiation of the parent body. They formed when various types of dust and small grains that were present in the early solar system accreted to form primitive asteroids....
s, a common type of stony meteorite composed of iron-bearing silicate

Silicate

A silicate is a compound containing an anion in which one or more central silicon atoms are surrounded by electronegative ligands. This definition is broad enough to include species such as hexafluorosilicate , [SiF6]2-, but the silicate species that are encountered most often consist of silicon with oxygen as the ligand...
s such as olivine

Olivine

The mineral olivine is a magnesium iron Silicate minerals with the formula 2siliconoxygen4. It is one of the most common minerals on Earth, and has also been identified in meteorites and on the Moon, Mars, and comet Wild 2....
and pyroxene

Pyroxene

The pyroxenes are a group of important rock-forming silicate minerals found in many igneous and metamorphic rock rock . They share a common structure comprised of single chains of silica tetrahedra and they crystallize in the monoclinic and orthorhombic systems....
. Infrared images reveal that Juno possesses an approximately 100 km-wide crater or ejecta feature, the result of a geologically young impact.

Observations

Juno was the first asteroid for which an occultation

Occultation

An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer. The word is used in astronomy and can also be used in a general sense to describe when an object in the foreground occults objects in the background....
was observed. It passed in front of a dim star

Star

A star is a massive, luminous ball of Plasma that is held together by its own gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth....
(SAO 112328) on February 19, 1958. Since then, several occultations by Juno have been observed, the most fruitful being on December 11, 1979, which was registered by 18 observers.

Radio signals from spacecraft in orbit around Mars

MARS

In cryptography, MARS is a block cipher that was IBM's submission to the Advanced Encryption Standard process. MARS was selected as an AES finalist in August 1999, after the AES2 conference in March 1999, where it was voted as the fifth and last finalist algorithm....
and on its surface have been used to estimate the mass of Juno from the tiny perturbations induced by it onto the motion of Mars. Juno's orbit

ORBit

ORBit is a Common Object Request Broker Architecture 2.4 compliant Object Request Broker . It features mature C , C++ and Python bindings, and less developed bindings for Perl, Lisp , Pascal , Ruby , and Tcl....
appears to have changed slightly around 1839, "very likely" due to perturbations from a passing asteroid, whose identity has not been determined. An alternate but less likely explanation is an impact by a sizeable body.

In 1996, Juno was imaged by the Hooker Telescope at Mount Wilson Observatory

Mount Wilson Observatory

The Mount Wilson Observatory is an astronomical observatory in Los Angeles County, California. The MWO is located on Mount Wilson , a 5,715 foot peak in the San Gabriel Mountains near Pasadena, California, northeast of Los Angeles....
at visible and near-IR wavelengths, using adaptive optics

Adaptive optics

Adaptive optics is a technology used to improve the performance of optics by reducing the effects of rapidly changing optical distortion. It is used in astronomical telescopes and laser communication systems to remove the effects of atmospheric distortion, and in retinal imaging systems to reduce the impact of ocular aberrations....
. The images spanned a whole rotation period and revealed an irregular shape and a dark albedo feature, interpreted as a fresh impact site.

External links

– Horizons can be used to obtain a current ephemeris

taken at Mount Wilson observatory
Mount Wilson Observatory

The Mount Wilson Observatory is an astronomical observatory in Los Angeles County, California. The MWO is located on Mount Wilson , a 5,715 foot peak in the San Gabriel Mountains near Pasadena, California, northeast of Los Angeles....

3 Juno

Characteristics

Observations

External links

See also