Asteroid 6 Hebe approaches opposition.

Asteroid 6 Hebe will reach opposition (the point at which it is directly opposite the Sun when observed from the Earth) at 4.46 pm GMT on Monday 25 August 2025, when it will also be at the closest point on its orbit to the Earth, 1.03 AU (i.e. 1.03 times as far from the Earth as the Sun, or about 153 787 000 km), and be completely illuminated by the Sun. While it is not obvious to the naked eye observer, asteroids have phases just like those of the Moon; being further from the Sun than the Earth, 6 Hebe is 'full' when directly opposite the Sun. As 6 Hebe is only about 205 km in diameter, it will not be visible to the naked eye, but with a maximum Apparent Magnitude (luminosity) of 7.6 at opposition, it should be visible in the Constellation of Aquarius to viewers equipped with a good pair of binoculars or small telescope. Because 6 Hebe is directly opposite the Sun in the sky, it will be best observed at around midnight local time from anywhere on Earth.

The orbits of 6 Hebe and the planets of the Inner Solar System, and their positions at 5.00 pm on Monday 25 August 2025. JPL Small Body Database.

Asteroid 6 Hebe was discovered on 1 July 1847 by Prussian amateur astronomer Karl Ludwig Hencke in the town of Driesen (now Drezdenko in Poland). As implied by the '6' in its modern designation, it was the sixth asteroid ever detected. It was given the name Hebe, in reference to the Greek goddess of youth by Carl Friedrich Gauss, director of the Göttingen Observatory. 

6 Hebe has a 1380 day (3.78 year) orbital period and an eccentric orbit tilted at an angle of 1.94° to the plane of the Solar System, which takes it from 1.94 AU from the Sun (i.e. 194% of the average distance at which the Earth orbits the Sun) to 2.92 AU from the Sun (i.e. 292% of the average distance at which the Earth orbits the Sun). As an asteroid that never comes within 1.666 AU of the Sun and has an average orbital distance less than 3.2 AU from the Sun, 4 Vesta is classed as a Main Belt Asteroid. 

6 Hebe is unusually dense for a large asteroid (denser than the Moon), containing about 0.5% of the mass of the Main Asteroid Belt, despite measuring only 205 km by 185 km by 170 km. This suggests that it is a solid object, unlike many large asteroids which are loosely connected 'rubble piles'. 

6 Hebe lies close to the '3:1 Kirkwood Gap' in the Main Asteroid Belt, an area where any asteroids present would have a 3:1 resonance with Jupiter (i.e. complete three orbits for every one orbit of Jupiter). This is an unstable area, devoid of asteroids, as any body in this area would likely be flung out by the tidal influence of Jupiter. Because of this, and its spectral profile (i.e. the specific wavelengths of light it reflects, which directly relates to its mineralogy, 6 Hebe is thought to be a likely parent body for H chondrites and IIE iron meteorites, two of the most common meteorite types on Earth, as well as the Near Earth Asteroids (4953) 1990 MU and 2007 LE. Furthermore, 6 Hebe appears to have an orbital and spectral relationship with a group of other Main Belt Asteroids, including bodies such as 695 Bella, 1166 Sakuntala, and 1607 Mavis which lie on the other side of the Kirkwood Gap, which have been tentatively identified as the 'Hebe Family' of asteroids, with a presumed common origin, either in a collision between two large bodies, or possibly from a single large body close to the Kirkwood Gap which was pulled apart by Jupiter's tidal influence.

See also...

Vesta at opposition.

Asteroid 4 Vesta will reach opposition (the point at which it is directly opposite the Sun when observed from the Earth) at 11.58 am GMT on Friday 2 May 2025, when it will also be at the closest point on its orbit to the Earth, 1.18 AU (i.e. 1.18 times as far from the Earth as the Sun, or about 176 825 000 km), and be completely illuminated by the Sun. While it is not obvious to the naked eye observer, asteroids have phases just like those of the Moon; being further from the Sun than the Earth, 4 Vesta is 'full' when directly opposite the Sun. As 4 Vesta is only about 525 km in diameter, it will not be visible to the naked eye, but with a maximum Apparent Magnitude (luminosity) of 5.7 at opposition, it should be visible in the Constellation of |Libra to viewers equipped with a good pair of binoculars or small telescope.

The orbit and position of 4 Vesta and the planets of the Inner Solar System 1t 12.00 noon GMT on Friday 2 May 2025.  JPL Small Body Database. 

4 Vesta has a 1326 day (3.63 year) orbital period and an eccentric orbit tilted at an angle of 7.14° to the plane of the Solar System, which takes it from 2.15 AU from the Sun (i.e. 215% of the average distance at which the Earth orbits the Sun) to 2.57 AU from the Sun (i.e. 257% of the average distance at which the Earth orbits the Sun). As an asteroid that never comes within 1.666 AU of the Sun and has an average orbital distance less than 3.2 AU from the Sun, 4 Vesta is classed as a Main Belt Asteroid. 

Asteroid 4 Vesta imaged by the Dawn space probe on 24 July 2011, from a distance of 5200 km. Björn Jónsson/NASA/JPL/MPS/DLR/IDA/Wikimedia Commons.

Asteroid 4 Vesta was discovered on 29 March 1807 by the German astronomer Heinrich Wilhelm Matthias Olbers, making it the fourth asteroid discovered, and the second by Olbers (who had discovered 2 Pallas on 28 March 1802). The asteroid was named Vesta in honour of the Roman goddess of the hearth. 4 Vesta is currently considered to be the second largest body in the Main Asteroid Belt, although uncertainty about the size of Asteroid 2 Pallas, means this is not completely certain.

Artist's concept of the Dawn space probe approaching 4 Vesta. NASA/JPL/CalTech.

The Dawn space probe orbited 4 Vesta from 16 July 2011 until 5 September 2012 (when it left to move on to Asteroid 1 Ceres). During this time it built up a detailed map of the surface of 4 Vesta, which revealed a northern surface covered with craters; apparently much older than the southern surface, suggesting that the asteroid was once a planetesimal on its way to growing into a planet.

High-resolution geological map of Vesta derived from Dawn spacecraft data. Brown colours represent the oldest, most heavily cratered surface. Purple colours in the north and light blue represent terrains modified by the Veneneia and Rheasilvia impacts, respectively. Light purples and dark blue colours below the equator represent the interior of the Rheasilvia and Veneneia basins. Greens and yellows represent relatively young landslides or other downhill movement and crater impact materials, respectively. NASA/JPL/CalTech/JSU.

See also...

NASA's Lucy spacecraft discovers asteroid 152830 Dinkinesh has a binary moon.

NASA's Lucy spacecraft flew past asteroid 152830 Dinkinesh on Wednesday 1 November 2023, discovering that the asteroid had a binary moon in the process. The Lucy spacecraft, launched from Cape Canaveral on 16 October 2021, was named after the Hominin fossil Lucy, which in turn was named after the Beetles song, Lucy in the Sky with Diamonds; the spacecraft carries a disc made of lab-grown diamonds for its L'TES (Lucy’s Thermal Emission Spectrometer) instrument. Lucy's primary mission is to explore Jupiter's Trojan Asteroids (asteroids permanently located in Jupiter's L₄ and L₅ Lagrange points. The trajectory of the probe was adjusted to make a flyby of 152830 Dinkinesh in January 2023, primarily as a way of testing its instruments on a suitable object.

An artist's concept depicting the Lucy spacecraft flying past the Trojan asteroid (617) Patroclus and its binary companion Menoetius. NASA/Southwest Research Institute/Wikimedia Commons.

The spacecraft first spotted the asteroid orbiting the 790 m asteroid at 4.55 pm GMT on 1 November 2023, when it was 430 km from the asteroid, passing it at a speed of 16 000 km per hour. At this time it was thought the second body was a single object roughly 220 m in diameter. However, the spacecraft took a second image looking back at the asteroid at 5.00 pm, revealing the satellite body to be a binary, made up of two similar sized objects in contact with one-another. 

A diagram showing the trajectory of the NASA Lucy spacecraft (red) during its flyby of the asteroid 152830 Dinkinesh and its satellite. NASA/Goddard Institute for Space Studies/Southwest Research Institute/Johns Hopkins University Applied Physics Laboratory/National Optical-Infrared Astronomy Research Laboratory.

While it was once thought that small asteroids lacked sufficient gravitational pull to have satellites, an increasing number have been shown to do so in recent years, and this is now thought to be quite common. Similarly, contact binaries, not predicted until they were discovered, are now fairly frequently observed. This is, however, the first time a moon of a small asteroid has been found to be a contact binary.

This image shows the asteroid Dinkinesh and its satellite as seen by the Lucy Long-Range Reconnaissance Imager  as NASA’s Lucy Spacecraft departed the system. NASA/Goddard Institute for Space Studies/Southwest Research Institute/Johns Hopkins University Applied Physics Laboratory.

Asteroid 152830 Dinkinesh was discovered by the Lincoln Near-Earth Asteroid Research Survey in Socorro, New Mexico on 4 November 1999. It was originally given the designation 1999 VD57, indicating that it was the 1429th object (asteroid D57 - in numbering asteroids the letters A-Z, excluding I, are assigned numbers from 1 to 25, with a number added to the end each time the alphabet is ended, so that A = 1, A1 = 26, A2 = 51, etc., which means that D57 = (25 x 57) + 4 = 1429) discovered in the first half of November 1999 (period 1999 V - the year being split into 24 half-months represented by the letters A-Y, with I being excluded). The longer designation 152830 implies that it was the 152 830th asteroid ever discovered, (these numbers are not assigned immediately, to prevent false sightings and repeat sightings of the same body being numbered). The name 'Dinkinesh' derives from 'Dink’inesh', which is the name given to the Lucy fossil in Amharic (the official language of Ethiopia, where the fossil was discovered), and means 'you are wonderful'. The name was chosen after it was decided that the asteroid would be a target for the Lucy spacecraft, and approved by the  International Astronomical Union's Working Group for Small Bodies Nomenclature on 6 February 2023.

The orbit and current position of asteroid 152830 Dinkinesh. JPL Small Body Database.

152830 Dinkinesh is calculated to have a 1185 day (3.24 year) orbital period, with an elliptical orbit tilted at an angle of 2.09° to the plain of the Solar System which takes in to 1.94 AU from the Sun (194% of the distance at which the Earth orbits the Sun, and some way the orbit of Mars) and out to 2.44 AU (2.44 times the distance at which the Earth orbits the Sun). It is therefore classed as a Main Belt Asteroid.

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter. 

Asteroid 14 Irene reaches opposition.

Asteroid 14 Irene will reach opposition (the point at which it is directly opposite the Sun when observed from the Earth) at 2.22 pm GMT on Sunday 24 January 2021, when it will also be at the closest point on its orbit to the Earth, 1.33 AU (i.e. 1.33 times as far from the Earth as the Sun, or about 199 264 000 km), and be completely illuminated by the Sun. While it is not obvious to the naked eye observer, asteroids have phases just like those of the Moon; being further from the Sun than the Earth, 14 Irene is 'full' when directly opposite the Sun. As 14 Irene is only about 152 km in diameter, it will not be visible to the naked eye, but with a maximum Apparent Magnitude (luminosity) of 9.3 at opposition, it should be visible in the Constellation of Cancer to viewers equipped with a good pair of binoculars or small telescope.

 

The orbit and current position of Asteroid 14 Irene. In The Sky.

14 Irene was discovered by English astronomer John Russell Hind on 19 May 1851. The number 14 implies that it was the fifteenth asteroid discovered, and it was named Irene after the Greek goddess of the same name, who was goddess of peace. It is also sometimes referred to as 1851 KA, implying the first asteroid (asteroid A) discovered in the second half of May 1851 (period 1851 K).

 

A three-dimensional model of 14 Irene that was computed using light curve inversion techniques. Josef Ďurech/Vojtěch Sidorin/Charles University/Wikimedia Commons.

14 Irene has an 1519 day (4.26 year) orbital period and an eccentric orbit tilted at an angle of 9.12° to the plane of the Solar System, which takes it from 2.16 AU from the Sun (i.e. 216% of the average distance at which the Earth orbits the Sun) to 3.02 AU from the Sun (i.e. 302% of the average distance at which the Earth orbits the Sun). As such it is considered to be a Main Belt Asteroid (an asteroid that is between 2.06 and 3.27 AU from the Sun and has an orbital eccentricity of less than 0.33 and an inclination of less than 20°).

See also...

Follow Sciency Thoughts on Facebook.

Follow Sciency Thoughts on Twitter.