Scientific Space: Important Astronomical Phenomena in January 2011

Astronomical Events

01st: Venus distance from Sun: 46.8^\circ W
02nd: 02:07 Moon conjunction Antares: 2.6^\circ S
02nd: 22:32 Mercury conjunction Moon: 4^\circ N
04th: 03:59 Earth at Perihelion: 0.9833 AU
04th: 09:14 Quadrantids Meteor Shower: ZHR = 120
04th: 16:52 Partial Solar Eclipse
08th: 22:59 Venus Greatest Elongation: 47^\circ W
09th: 21:59 Mercury Greatest Elongation: 23.3^\circ W
15th: 20:39 Moon conjunction Pleiades: 1.3^\circ N
29th: 07:53 Moon conjunction Antares: 2.7^\circ S
30th: 00:26 Moon at southernmost point: 24.2^\circ S
30th: 11:36 Venus conjunction Moon: 3.7^\circ N

Full version: http://kexue.fm/AC.html

Moon Phases

04th: 17:03 New Moon
12th: 19:31 First Quarter
20th: 05:21 Full Moon
26th: 20:57 Last Quarter

January 4: Quadrantids Meteor Shower Peak

Accompanying the New Moon, the Quadrantids meteor shower, known as one of the three major meteor showers in the Northern Hemisphere, will reach its peak. This is a cross-year meteor group, with its active period lasting from December 28, 2010, to January 12, 2011. During this time, the northern regions of China have many clear days and long nights, which are suitable for astronomical observations, although observers must face the test of cold weather.

For a meteor group, the higher the altitude of the radiant point, the closer the number of observed meteors will be to its theoretical Zenithal Hourly Rate (ZHR). The radiant point of the Quadrantids is located between Draco and Boötes, and its declination can reach 49^\circ during the peak. This means that if we observe from regions north of 40^\circN latitude, the radiant point almost never sets. Especially for places around 40^\circN, the radiant point will be near the zenith when it culminates, which is very favorable for observation. However, in early January, the culmination time of the radiant point is approximately 8:00 AM local time, and we cannot perform visual meteor observations during the day. Friends will find that during the active period of the Quadrantids, the radiant point gradually rises throughout the night, meaning observation conditions improve as dawn approaches.

The peak of the 2011 Quadrantids is likely to occur at 9:00 AM Beijing Time on January 4, at which time the ZHR will reach 120. Observation conditions will be ideal from Central Asia to all of Europe. According to the International Meteor Organization’s forecast, the rate may remain at a high level for about 4 hours before and after this time. For China, the observation conditions before dawn on the 4th are relatively ideal. During this active period, the Moon is very cooperative, making this a rare opportunity to observe a high-rate meteor shower without moonlight interference this year. The exact time of the New Moon is 8 hours after the predicted peak of the Quadrantids, and a wonderful partial solar eclipse will also take place at that time, so this observation will not be affected by moonlight. However, the Perseids and Geminids in 2011 will not be so lucky.

The meteors of the Quadrantids are mostly white and include many bright meteors, with a velocity of 41 km/s. They have distinct characteristics and are worth observing. However, it is a reminder that in the days following the peak, the rate will decay significantly, so it is best to schedule observations between the night of the 3rd and the early morning of the 4th.

January 4: Partial Solar Eclipse

In 2011, there will be four partial solar eclipses globally, but only two will be observable from a few regions in China. The partial solar eclipse on January 4 begins at 14:40 Beijing Time from Africa and Western Europe, passing through Northern Africa, most of Europe, the Middle East, and Central Asia, and ends at 19:01 in parts of Xinjiang, Tibet, Qinghai, and Gansu in Western China. The maximum magnitude is 0.86, visible in Sweden. However, due to the high geographical latitude near the polar night zone, the local observation time will be very short.

In China, only the sparsely populated northwestern regions can observe this partial solar eclipse, and the maximum visible magnitude will not exceed 0.4. Only the extreme western regions can see the entire process from first contact to last contact, while other regions will only see the eclipse during sunset. For example, in Urumqi, the first contact occurs at 17:17, with the Sun’s altitude at nearly 11^\circ. The maximum eclipse (magnitude 0.23) occurs at 18:08, when the Sun’s altitude is only about 5^\circ. Shortly thereafter, the Sun will set, making it impossible to observe until the last contact.

Of the three subsequent partial solar eclipses, only the one on June 2 will be visible as a "sunset eclipse" in parts of Northeast China, while the other two occur near distant Antarctica and will not be visible from China. I would also like to remind everyone that although the eclipse occurs at sunset and the sunlight might not be as blinding if the weather is not perfectly clear, you still need to take light-reduction measures when observing the Sun with a telescope. The retinal nerves of the human eye are not sensitive; by the time you feel discomfort, it may already be too late.

January 8: Venus Greatest Western Elongation

Since December 2010, Venus has entered a better observation period. In the early morning, as long as the weather is clear, early risers can see it in the southeastern sky. Venus is called the "Morning Star" (Qi Ming Xing) when it appears in the morning due to its high brightness. On January 8, 2011, it will reach its greatest elongation position west of the Sun, with an angular distance of approximately 47^\circ and a magnitude of -4.6. Since its declination is slightly higher than the Sun’s, the observation conditions for Venus are excellent. For regions near 40^\circN latitude, the altitude of Venus at sunrise can reach about 30^\circ.

In a telescope, Venus appears with a phase similar to a last quarter moon. This is because it does not emit light itself and its orbit around the Sun is inside Earth’s orbit. 400 years ago, when Galileo first observed Venus with a telescope, he discovered its phase changes, which strongly confirmed Copernicus’s heliocentric theory. Interested friends can use a long-focal-length telescope connected to a web camera for video capture and obtain clearer images of Venus through post-processing and stacking. Of course, such observations place high demands on weather and timing. First, the atmospheric seeing must be ideal; if the shimmering is too intense, it will be impossible to focus, and there will be few usable frames in the captured video. Second, if we observe when Venus is at a high altitude, the background sky will be very bright, but the lower the altitude, the more obvious the atmospheric interference becomes—this is clearly a contradiction. We can choose a clear morning to continuously photograph Venus and then select the best segment of video for processing.

After the greatest western elongation, the declination of Venus will gradually decrease while the Sun’s declination increases, so its altitude at sunrise will drop rapidly, and good observation conditions will not last long.

January 9: Mercury Greatest Western Elongation

Just one day after Venus’s greatest western elongation, another inferior planet, Mercury, will also reach its greatest western elongation. In 2011, Mercury will have seven elongations, four of which offer good observation conditions. During this western elongation on January 9, the angular distance between Mercury and the Sun will reach over 23^\circ, the brightness will be about -0.3 mag, and the altitude at sunrise will be about 15^\circ, which is favorable for observation.

Due to its small maximum angular distance from the Sun, Mercury is difficult to see; even the famous astronomer Copernicus is said to have never observed it in his lifetime. However, for amateur astronomers, the observation conditions for three western elongations and one eastern elongation of Mercury in 2011 are very good. In January, Venus and Mercury are not far apart, and their observation conditions are good before the elongation. On the mornings of the 1st and 2nd, we even have the opportunity to see the two planets in conjunction with the waning crescent moon. You can find a place with an open eastern horizon and use a camera to capture the "double stars accompanying the moon."

January 2011 Sun, Moon, and Planetary Dynamics

• Sun: At the beginning of the month, the Sun’s apparent Right Ascension and Declination are 18h 43m 43s and -23^\circ 03’ 26”; at the end of the month, they are 20h 52m 10s and -17^\circ 34’ 48”. This month, the Sun moves from Sagittarius to Capricorn. A partial solar eclipse occurs on the 4th at 17:00, visible in the extreme northeastern Pacific, northern Africa, Europe (except the extreme north), western Asia, and the northern Arabian Sea.

• Moon: The Moon passes apogee and perigee on January 10 at 14:00 and January 12 at 08:00, respectively. The phases of New Moon, First Quarter, Full Moon, and Last Quarter occur on the 4th at 17:03, 12th at 19:31, 20th at 05:21, and 26th at 20:57. On the 7th at 06:00, the Moon occults Mars, with Mars 0.5^\circ south of the Moon.

• Mercury: In January, Mercury is a morning star, appearing in the southeastern sky at dawn. On January 9, Mercury reaches its greatest western elongation, with an angular distance of 23^\circ from the Sun, an altitude of about 15^\circ at sunrise, and a brightness of about -0.3 mag, marking the first favorable opportunity to observe Mercury this year. After the elongation, Mercury moves closer to the Sun each day.

• Venus: In January, Venus moves from Libra into Ophiuchus, located in the southeastern sky before sunrise. On January 8, Venus reaches greatest western elongation, 47^\circ from the Sun, with a brightness of about -4.6 mag and an altitude of about 30^\circ at sunrise, making it the best period to observe Venus. After the elongation, Venus begins to approach the Sun; its altitude at sunrise drops from 30^\circ to about 24^\circ by the end of the month, with a brightness of about -4.4 mag, still a good period for observation. Conjunctions with the Moon occur on the 1st (Venus 7^\circ north), 2nd (Venus 4^\circ north), and 30th (Venus 3^\circ north). On the 16th at 06:00, Venus is in conjunction with Antares, 8^\circ north of the star.

• Mars: In January, Mars moves prograde from Sagittarius through Capricorn. It is close to the Sun and difficult to observe.

• Jupiter: In January, Jupiter moves prograde from Aquarius to Pisces. It is visible in the southeastern to southwestern sky at sunset during the first ten days, with a brightness of about -2.3 mag. Its setting time advances from around 23:00 to 21:30, and the observable time gradually decreases. On the 2nd at 22:00, Jupiter is in conjunction with Uranus, 0.6^\circ south of Uranus. On the 11th at 01:00, Jupiter is in conjunction with the Moon, 7^\circ south of the Moon.

• Saturn: In January, Saturn moves in Virgo, rising from the east around 23:40, with a brightness of about +0.7 mag. Observation is favorable in the latter half of the night. On the 25th at 18:00, Saturn is in conjunction with the Moon, 8^\circ north of the Moon. On the 27th at 16:00, Saturn is stationary.

• Uranus: Moving in Pisces with a brightness of 5.9 mag. On the 10th at 23:00, Uranus is in conjunction with the Moon, 6.5^\circ south of the Moon.

• Neptune: Moving from Capricorn to Aquarius with a brightness of 8.0 mag.