Stargazing with John Stapleton from Torbay Astronomical Society:
On October 16, NASA launched its Lucy mission.
This is the longest and most detailed mission to the asteroids so far conceived.
The asteroids are viewed as relics, or fossils, of the very early solar system and may hold clues to the formation of that system and to the origins of life within it.
For this reason, the mission has been named Lucy after the earliest australopithecine hominid fossil skeleton known.
Some asteroid flyby missions have been made before but they have been single encounters.
Even within the so-called Asteroid Belt, the average distance between asteroids is about 600,000 miles (one million kilometres) so encountering more than one on a single journey would be extremely difficult.
However, Lucy is headed towards Jupiter where a large number of asteroids have been captured by the giant planet’s gravity and now orbit the Sun in two Lagrange points within the planet's orbit - these Lagrange points are stable areas where all the component gravitational forces balance each other out - this will enable Lucy to fly by and study eight asteroids in a single mission.
Jupiter’s Trojan asteroids are all named after characters from stories about the Trojan Wars and lie in the planet’s orbit at two Lagrange points known as L4 and L5.
Those at L4 precede Jupiter by about sixty degrees and are given the names of Greek Characters (L4 is known as the Greek camp) and those at L5 (the Trojan camp) are given the names of Trojan characters and trail Jupiter by about sixty degrees.
Lucy will take 12 years to complete its mission.
After getting two gravity assists from orbits around the Earth, the probe will head out into deep space to rendezvous with a main belt asteroid known as 52246 Donaldjohansen - named after the discoverer of the Lucy fossil - in April 2025.
After that, it will take another two years to reach the L4 Greek camp and the asteroids 3548 Eurybates, and its satellite known as Queta, and 15094 Polymele.
Two more asteroids, 11351 Leucus and 21900 Orus, will be visited in 2028, then Lucy will head back to Earth in order to get another gravity assist and course change to send her back to Jupiter, this time, to the Trojan camp where she will study the double asteroid 617 Patroclus-Menoetius in 2033.
All these asteroids are very dark in colour and do not have significant spectra.
The dark colouration is thought to be material called tholins which contains primitive organic molecules.
One of the instruments on board the probe is L’TES which is an infrared spectrometer capable of determining the composition and structure of the asteroids’ surfaces.
A major component of this instrument is a disc of lab-grown diamonds.
So, very fitting as the original Lucy fossil skeleton was named after the song by the Beatles.
The Star Chart
The sky will look like the chart on November 7 at 9pm and again on November 22 at 8pm.
And four minutes earlier on each successive night e.g. 8.56 on November 8.
To use the chart, hold it above your head while facing south so that you can look directly from the chart to the sky.
Please note all times given in this article are in GMT and as the clocks have changed that is the current time.
Sun: From the beginning to the end of the month the period of dark sky increases by an hour. At the beginning of the month the Sun sets before 5pm and by the end of the month by 4:15 pm after which there is the twilight period. The nights are really drawing in now.
Mercury: Mercury is visible early this month in the morning sky and rising about 90 minutes before sunrise on November 1. On November 11, Mercury is close to Mars and the two planets ride about 60 minutes before sunrise. Mercury is currently seen against the background stars of Virgo.
Venus: Venus is an evening object throughout the month, setting about a hundred minutes after the Sun on November 1. At this time Venus is seen against the background stars of Ophiuchus but it will move into Sagittarius as the month progresses and remain visible for two hours after the Sun has set. When Venus is seen so low in the sky it is often mistaken for a UFO. Jupiter is also nearby and only a little higher in the sky and is also often mistaken for a UFO. Observers also need to bear in mind that one of the dates of prolific UFO sightings falls on November 5!
Mars: Mars is now a morning object seen in Virgo. It is now quite faint and difficult to observe so being close to Mercury on November 11 would be an interesting observation or make an interesting image.
Jupiter: The largest planet actually rises in the East during daylight hours throughout the month and so is visible throughout the evening and seen against the background stars of Capricornus. In the darker skies, the contrast allows the coloured bands and zones on the surface of the planet to be distinguished more easily with small telescopes as can the Great Red Spot, a colossal hurricane, greater in diameter than the planet Earth. The Galilean moons can be seen with a good pair of binoculars or a small (bird-spotting) telescope. DSLR images of the planet will also pick up the moons. These moons orbit Jupiter such that we sometimes see them pass between the Earth and the giant planet along our line of sight. Watch out for small black dots seen against the surface of Jupiter itself; again more easily seen in the contrast with darker skies. The moons Europa and Io will cast their shadows onto Jupiter on November 14 at 8.30pm.
Saturn: The ringed planet can also be found against the stars of Capricornus, rising in the East during daylight hours and visible all evening. The rings are beginning to open out, from our point of view and are consequently becoming brighter. Saturn’s largest moon, Titan, can be seen above and to the right of the planet with a good pair of binoculars or a small telescope.
Uranus and Neptune: Uranus is visible all night long throughout October and is seen against the background stars of Aries and close to the Pleiades star cluster. At magnitude 5.8 it is visible in binoculars. Look for a tiny greenish disc compared to the pinpoints which are the stars. Neptune is seen against the background stars of Aquarius (below the asterism known as the Square of Pegasus) and lies due south on November 4. At magnitude 7.8 it will require large binoculars or a small telescope to find it. Neptune displays a smaller and truly blue disc compared to that of Uranus although it will appear only as a bluish star to most small instruments
Meteor shower: There are two meteor showers due in November. The first, on the night of November 17, is the Leonids. The Leonid shower is associated with a comet called Temple-Tuttle which has a 33-year orbit around the Sun. This is the shower which, once every 33 years, produces a meteor storm with thousands of meteors seen in a night. The last such storm was expected in 1999 but did not occur until 2001, so the next storm is expected sometime between 2032 and 2035. The nearly full moon will make observation difficult this year. The second shower this month is the Taurids which seem to emanate from a point near the Pleiades. These meteors are particularly bright and are not affected by strong moonlight. In fact this shower contains large meteors that can produce fireballs – defined as bright enough to cast shadows. This shower is associated with a comet called Encke, which has one of the shortest orbital periods of any comet; just 3.3 years.
Comet: There are no bright comets expected this month but one of the “background” faint periodic comets seems to be undergoing an outburst and increasing in brightness. This comet, known as 29P Schwassman-Wachmann, was discovered in 1927 and has an orbital period of just under 15 years. It is known to be an unusual icy body referred to as a centaur because much of its orbit lies between Jupiter and Neptune. 29P is believed to be covered in ice volcanoes which account for the regular outbursts in brightness. The comet is faint but is currently located in the constellation of Auriga.
The New Moon occurred on November 4 with First Quarter on 11th, Full Moon then follows on November 19 and Last Quarter on November 28.
Data supplied by Simon Harding, Observations Secretary Torbay Astronomical Society
The next meetings of the Torbay Astronomical Society, complying with the current Covid regulations, will be held at Torquay Boys' Grammar School. The next meeting will be an observational evening this evening, November 4, where members will be focussing on M15, M33, M34, NGC7662, Almaach, Jupiter and Saturn. On Thursday, November 18, Roger D Cooper will give a talk “Life After Skylark”. For details contact the Secretary TAS on email@example.com. Visitors and prospective members especially welcome.
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