Scientific Space: Important Astronomical Phenomena in November 2010

November: Maxima of the South and North Taurid Meteor Showers

Although their radiants are very close, the South and North Taurids are still distinguished as two different meteor streams. Since their parent comet is the same, Comet 2P/Encke, the two meteor streams share many commonalities, such as the predominantly white color of the meteors and the relatively slow velocity of the meteoroids.

The South and North Taurid meteor streams begin their activity as early as September 25, and their active period can last for about two months, basically ending by November 25. The maximum of the South Taurids will arrive first, likely appearing on November 5 this year, while the North Taurids will reach their maximum around November 12. In reality, the flow rates of both the South and North Taurids are very small; even at their peak, their ZHR (Zenithal Hourly Rate) is only about 5. This means it is quite difficult to see even 2 to 3 meteors from the stream per hour. Therefore, few amateur astronomers specifically observe the Taurids; they are often seen or photographed incidentally while observing the Orionids or Leonids.

Speaking of the South and North Taurids, one cannot ignore their parent comet, 2P/Encke. This is a famous short-period comet that takes only 3.3 years to orbit the Sun. It was also one of the first comets for which humans calculated an orbit. Due to its nucleus being frequently affected by the Sun’s immense gravity and radiation, it constantly ejects material, and the brightness of the comet during recent returns has shown a clear downward trend. Comet 2P/Encke returned this year as well, passing perihelion on July 18. Unfortunately for observers on Earth, the angular distance between the comet and the Sun was too close at that time, making observation very difficult.

Although Comet 2P/Encke is no longer as spectacular as it once was, the South and North Taurid meteor showers are still worth watching. Their meteoroid velocities are between 27 and 29 km/s, and there are many bright meteors, making them very suitable for visual and photographic observation. The return of the parent comet also gives us more to look forward to regarding these two meteor streams. Furthermore, the lunar phase during the Taurid maxima this year ranges from a waning crescent to a waxing crescent, which will have almost no impact on observations.

Because the radiant is close to the anti-solar point on the ecliptic, many astronomers have begun to suspect that the South and North Taurids are part of the autumnal anti-helion source. This means their formation is likely related to solar gravity. Of course, this also implies that during the active period of the meteor shower, the radiant rises at sunset and sets around sunrise, allowing us to see meteors from the stream almost all night long.

November 16: Jupiter Conjunction with Moon

After the onset of autumn, if you look up at the sky at night, the first thing you will notice is definitely the bright Jupiter. After Jupiter’s opposition on September 20, its rising time has gradually moved earlier. If you use a telescope to observe Jupiter, its four bright Galilean moons will be the biggest highlight. Of course, if your telescope’s resolution is high enough, you might also see the colored cloud belts on its surface.

This month, the main observable time for Jupiter is during the first half of the night. It culminates at approximately 20:00 local time, with a brightness of about -2.7 magnitude, making observation conditions very ideal. From the night of November 16 to the early morning of the 17th, the angular distance between Jupiter and the waxing gibbous moon (11th day of the lunar month) will be very close, reaching a minimum of about 6. The Jupiter-Moon conjunction will take place around midnight on the 17th.

Jupiter-Moon conjunctions are not rare; they occur every month. However, the phase of the moon during the conjunction varies. For example, a conjunction occurring around the time of Jupiter’s opposition involves a full moon. Two months later, it will be a waxing gibbous moon, and two months after that, the moon near Jupiter will be at its first quarter, followed by a crescent moon. Full moons and waxing gibbous moons are very bright, and when photographing a Jupiter-Moon conjunction, the moon is likely to be overexposed. In contrast, a waxing or waning crescent moon is easier to photograph with Jupiter.

November 18: Leonid Meteor Shower Maximum

I believe that every friend who, like me, observed the 2001 Leonid meteor shower will find it hard to forget that scene for the rest of their lives. Unfortunately, although we are full of anticipation every year, it has not brought us such a surprise again. In 2009, the Leonids experienced a small-scale outburst, and the lunar phase was very favorable for observation, but the flow rate was still far from the level of a meteor storm.

The active period of the Leonids is from November 10 to 23. According to the forecast of the International Meteor Organization (IMO), the maximum in 2010 will occur around 05:15 Beijing time on the morning of November 18. This time is clearly suitable for astronomical enthusiasts in China. The waxing gibbous moon (12th day of the lunar month) will also set around 03:00, by which time the radiant will have risen quite high, marking the start of the best observation time for the Leonids. However, this year’s meteor shower, brought to us by Comet 55P/Tempel-Tuttle, is not expected to have a large-scale outburst, with the ZHR at maximum estimated to be around 20. Even so, the Leonids are still worth observing. Ideally, one should complete standard visual observations and create reports to submit to the IMO.

Finally, a reminder to everyone: the radiant of the Leonids rises around 00:00 local time, so observation is mainly during the second half of the night. For most areas in northern China, the second half of the night in late November is already very cold. If you plan to observe the Leonids, be sure to arm yourself with thick winter clothing and pay attention to staying warm. It is also best to go with others; students’ observation activities must be conducted under the guidance of teachers or parents.