October is not known for a single large meteor stream, like August with the Perseids or December with the Geminids. Instead, there are many weaker streams, which overlap and make a look upwards worthwhile.
Many inconspicuous meteor streams
In October there are quite a few shooting star streams, which would hardly be worth mentioning on their own. They are only good for 2 to 5 meteors per hour. The first one is the October Camelopardalids. This is a faint and only since 2005 documented meteor stream, its radiant lies in the inconspicuous constellation Giraffe – it is found between the Big Dipper, Cassiopeia and Polaris. Other more inconspicuous streams are the Delta Aurigids with radiant in the Fuhrmann, the Epsilon Geminids with radiant in the constellation Gemini and the Leo Minorids in the Leo Minor. But between these many faint meteor streams there are also some for which a closer look is worthwhile.
They have their radiant in the constellation Dragon (lies around Polaris) and have their peak between October 6 and 10. They are also called Giacobinids because they originate in the dust trail of comet 1P/Giacobini-Zinner. They are comparatively slow and are easy to see when they fall. This year the observing opportunities are favorable because in the evening hours the radiant is high in the sky and the still half illuminated moon rises only after midnight. For the Draconids a typical fall rate of 10 meteors per hour is given, but the variation is enormous. For some years true meteor storms with hundreds of falling stars per hour are documented. These years include 1933, 1946, and 2011. In October 2011, for example, the fall rate was 300 me teors per hour. In 2018, it was 150 meteors in each of a short 4-hour window. The actual maximum is expected around October 9, but cannot really be narrowed down sharply in time.
Possible fireballs from Taurus – the Taurids
This meteor stream is divided into two parts – the northern and southern Taurids. The origin lies in debris of the comet 2P/Encke (or Encke's comet). It has the shortest period of all known comets and needs only 3.3 years for one orbit!
Fig. 1: Image of comet 2P/Encke; Source: Wikipedia
It draws its orbit between those of Mercury and Jupiter. But the latter with its enormous gravitational field makes sure that the debris field is widely distributed. In addition it tugs also at the comet itself, so that larger fragments can result – also the well-known Tunguska event on 30 June 1908 is brought in connection with this comet. Sometimes also some planetoids come into consideration as further origin bodies. The period of the Taurids extends from late summer to late autumn, the maxima partly overlap. The southern Taurids have one between October 10 and 13, a second around November 5. The fall rates are low with only 5 meteors per hour, but with luck they can be very spectacular. The Taurids are known for fireballs or flares (in the literature also called bolides)! The potentially larger debris take longer to burn up. They glow very brightly and leave a trail, sometimes they can be seen breaking up or even heard in extreme cases.
Fig. 2: Image of a fireball with the plasma lighting up as well as an image of a breaking meteor; Source: Wikipedia
Who has observed something like this, knows afterwards the difference to normal shooting stars! The chance exists also this year, but of course there is no guarantee.
The Orionids – bright and fast
The radiant of this meteor stream lies in the constellation Orion, a bit above the prominent orange left shoulder star Betelgeuse.
Fig. 3: Position of the radiant in the Orionids, left above Betelgeuse; Source: Wikipedia
The source body is the well-known Halley's comet. The period of activity extends from October 2 to November 7, overlapping the previously mentioned streams. The actual maximum is reached around October 21/22, this year the moon is already half full again at this time, but sets after 11 pm. The Orionids are very fast, entering the Earth's atmosphere at 60 kilometers per second. Due to this high speed very high temperatures are generated, this again provides a strong ionization of the air and a long and strong ionization trail. This tracer can sometimes be seen for some time after the actual shooting star. Fireballs are also possible in this case.
Which shooting star belongs to which meteor stream is not so important. Whether only a cursory look upwards, or a more extended observation phase – it can be quite worthwhile at this time of the year.
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