Scientific Space: Important Astronomical Phenomena in November 2009

01st: Mars near the Beehive Cluster

North and South Taurid Meteor Showers

The Taurid meteor shower is associated with Comet Encke and is named because its radiant appears to come from the constellation Taurus. Because it occurs from late October to early November, coinciding with the Halloween season, it is also known as the "Halloween Fireballs."

It is generally believed that the Taurids originate from Comet 2P/Encke, a comet with a return period of only 3.3 years. However, in recent years, another view has emerged suggesting that these two meteor showers are part of the Anti-Helion Source (ANT). In short, the cause is still under intense debate. The activity of the meteor shower lasts for a long time, much longer than typical minor meteor showers. The particles of the Taurids are also composed of relatively heavy materials, mainly small pebbles rather than ordinary dust grains.

Typically, when the Taurids appear, about 7 meteors per hour can be seen slowly streaking across the sky, with a speed of approximately 27 km/sec (or 65,000 miles per hour). If they are large enough, some can become spectacular bolides, sometimes even producing sound.

Due to the influence of planetary gravitational fields, particularly Jupiter’s, the Taurids are identified observationally as two branches, the South Taurids and the North Taurids. In reality, these are two cross-sections of the stream of debris as it spans through space.

November 9: Mars Conjunction with the Moon

After more than a year of waiting, it is finally time to observe Mars again. Looking at the planetary data table below, you can see that Mars is already the planet closest to us. Why not take out your telescope and witness the red splendor of "Yinghuo" (Mars)? Currently, Mars is located in the constellation Cancer, which has no bright stars. Its brightness has increased from magnitude 1 in the summer to magnitude 0, making its position in the sky particularly prominent!

This month, there are two interesting astronomical phenomena related to Mars. First, on the 1st and 2nd, Mars is near the Beehive Cluster (M44). A few days later, on November 9, we can enjoy the beautiful phenomenon of "Mars conjunction with the Moon." Generally speaking, "conjunction with the Moon" is used in a broad sense; when the Moon moves to within a few degrees of a bright star, it can be said that the star is in conjunction with the Moon. This is a great opportunity to view bright stars. This time, the Moon will pass within 5 degrees of Mars. However, the relatively bright Moon may make observation difficult, so let’s rise to the challenge!

November 18: Leonid Meteor Shower Peak

Finally, we come to our main protagonist! This year’s major meteor shower—the Leonids—is something we all look forward to!

Pick up your pen and mark November 18, 2009, because the "King of Meteors" may make a magnificent return on this day.

The parent body of the Leonid meteor shower is Comet 55P/Tempel-Tuttle, with a return period of 33 years. For many astronomy enthusiasts, the Leonids were their true introductory teacher. The two large-scale outbursts in 1998 and 2001 led many friends to fall in love with astronomy and become passionate about meteor shower observation. Recently, according to the revised calculation results by Vaubaillon, the Earth will be closest to the 1466 dust trail at 05:44 on November 18, 2009 (Beijing Time, the same below), at a distance of about 50,000 kilometers. At that time, the peak Zenithal Hourly Rate (ZHR) may reach as high as 950; at 05:51, the Earth will graze the 1533 return material at a similar distance, with a peak ZHR potentially reaching 600. The cumulative peak rate could reach levels of 1000–1500 per hour. Vaubaillon noted, "This encounter is very similar to 1998." At that time, the Earth encountered the 1333 dust trail at a distance slightly further than in 2009 (about 100,000 kilometers), but the 1333 trail produced a large number of fireballs. Therefore, although the rate was not extremely high (ZHR about 340), it was very spectacular. "If the model is correct, the proportion of fireballs in 2009 will not be as large as in 1998," Vaubaillon said. However, predictions from several other scientists are far less optimistic. Esko Lyytinen and Marku Nissinen gave an encounter time for the 1466 and 1533 trails between 05:00 and 06:00 on the 18th, with a cumulative peak rate of about 120 per hour; Mikhail Maslov gave a similar peak time with a cumulative peak rate of about 130–140 per hour.

However, yesterday (October 17), Jeremi Vaubaillon released a new forecast after further calculations. The forecast indicates that the maximum ZHR produced by the encounter with the 1466 and 1533 return materials will be about 200 per hour, with the two trails producing rates of about 115 and 80 per hour respectively. This is a significant downward revision from the original estimate of 500–1500, but the predicted peak time remains around 05:50 Beijing Time on the 18th. At this point, all current forecasts for time and rate are converging. But Jeremi pointed out that because the trails encountered this time are very ancient, there is a certain degree of uncertainty in the forecast, making observational verification very important. In addition, the Earth is expected to encounter the 1567 and 1102 return materials, but the peak times are not suitable for observation in China.

Looking at the weather, according to EECRA nighttime cloud cover observation data, the average cloud cover in the vast areas north of the Yangtze River will be between 30% and 40%, and slightly lower in the Qinghai-Tibet Plateau. South of the Yangtze River, it will be between 50% and 70%. The probability of a completely clear night is about 50% for North China, 40% for Northwest China, 30% for the Yangtze River basin, and only around 20% for South China.

Considering that the moon phase conditions in 2009 are excellent and the peak center falls in China, and given the "divergent" predictions for the meteor rate, it remains to be seen who will emerge victorious. I hope everyone has good luck during those days and can witness the roar of the Lion King, because it might be another 20 years before the next such event.

21st: \alpha Monocerotid Meteor Shower Peak

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