In the Transient Sky – November 2012
November 1, 2012 1 Comment
November 2012 Highlights * Leonid meteor shower peaks on the morning of November 17 though rates will be low * Jupiter and the Moon pair up on the evenings of the 1st and 28th * Venus and Saturn pair up on the morning of the 26th-27th * Venus, Mercury and Saturn are all visible in a line at the end of the month Note: If anyone has pictures or observations of these objects/events and want to share them with my readers, send them to the Transient Sky at <firstname.lastname@example.org>.
Mercury – Mercury starts the month very low in the southwest after dusk. It is probably too low for most observers. Luckily it appears in the morning at the end of the month.
Mars – Mars glows at a rather meager +1.2 magnitude this month low in the southwest after dusk. It is only visible for anout an hour after sunset as it continues its slow descent towards the horizon. Use the Moon to find Mars on the evenings of the 15th and 16th.
Jupiter – Jupiter is heading towards its December 2nd opposition. At the start of the month it rises in the northeast around 7:30 to 8:00 pm. On the evening of the first, it makes a spectacular pair with the Moon between the horns of Taurus. The two pair up again on the evening of the 28th. At magnitude -2.6 to -2.7 it is the brightest “star” in the sky with the exception of early morning Venus.
Venus – Venus rises about 2 hours before the Sun this month. In a telescope the planet will appear more than half-illuminated (about 80%). At magnitude – 4.1, Venus is by far the brightest ‘star’ in the morning sky. This November Venus makes a close pairing with the star Theta Virginis on the 12th and 13th, a more distant pairing with 1st magnitude Spica on the 17th and a rather close pairing with Saturn on the 26th and 27th. The Moon also passes to the south of Venus on the morning of the 11th. During the last week of November, Venus, Saturn and Mercury
Saturn – Saturn is an early morning object. Venus passes very close to Saturn on the mornings of the 26th and 27th.
Mercury – The innermost planet pops above the southeast horizon just before dawn during the last week of the month. It is the lower left planet in a line made up of Saturn-Venus-Mercury.
The year is usually split in 2 with January through June having low rates with few major showers while July through December have high rates with many major showers. Meteor activity is still near an annual this month.
Sporadic meteors are not part of any known meteor shower. They represent the background flux of meteors. Except for the few days per year when a major shower is active, most meteors that are observed are Sporadics. This is especially true for meteors observed during the evening. During November mornings, 10 or so Sporadic meteors can be observed per hour from a dark moonless sky.
Major Meteor Showers
Leonids (LEO) [Max Date = Nov. 17, Max ZHR = ~10-15 per hour]
The Leonids are the result of dust released by Comet Tempel-Tuttle. The comet resides on an orbit that spans from just inside the orbit of the Earth (0.98 AU) to slightly beyond the orbit of Uranus (19.7 AU). It takes the comet ~33 years to orbit the Sun. The the comet last passed perihelion (closest distance to the Sun) in 1998 and was well observed at that time.
The first recorded appearance of the Leonids was in 902 AD when the shower was seen from Italy and Egypt. For the next few centuries, impressive Leonid displays were observed every 33 to 200 years or so.
Two Leonid storms stand out from all the others. On 1833 November 13, the entire eastern United States was awaken to a sight very few had every seen. The sky appeared to be filled with meteors. Modern researchers now know the cause of this outburst. It is estimated that a rate of up to ~70,000 meteors per hour was observed. That works out to ~20 meteor per second.
The 1833 storm marks the dawning of the modern age of meteor science. It was due to observations of this storm that astronomers first recognized that meteors originate in space. About 30 years later, after the discovery of Comets Swift-Tuttle (parent of the Perseids) and Tempel-Tuttle (the parent of the Leonids), the connection between comets and meteor showers was made.
The 1833 storm ranks as one of the 2 best meteor displays in recorded history. 133 years after the 1833 storm, the Leonids once again set the skies ablaze. On the night of 1966 November 17, the western United States experienced a storm just as strong as the 1833 storm.
When the comet returned in 1998, there were many predictions for spectacular Leonid activity. Though meteor rates never got close to that seen in 1833 or 1966, rates as high as a few thousand meteors per hour were observed in multiple years. The best meteor shower I have ever seen was the 1998 Leonid fireball display. Though I would observe Leonid displays with much higher rates of meteors, the sheer number of extremely bright meteors in 1998 was breathtaking.
Unfortunately no major display is forecast for 2012. Rather rates should be a meager 10-15 per hour for observers under dark skies.
The Leonids appear to come from an area in the “sickle” of Leo. This area, called the radiant, rises around midnight local time. It is best to wait till the radiant is high in the sky before looking for meteors (say 2am). The radiant is highest around the start of dawn. Meteors can appear anywhere in the sky so you don’t have to look at the radiant.
Minor Meteor Showers
Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Info on many minor showers are provided on a weekly basis by Robert Lunsford’s Meteor Activity Outlook.
Additional information on these showers and other minor showers not included here can be found at the International Meteor Organization’s 2012 Meteor Shower Calendar.
Naked Eye Comets (V < 6.0)
None this month.
Binocular Comets (V = 6.0 – 8.0)
None this month
Small Telescope Comets (V = 8.0 – 10.0)
The surprise comet of the year, little 168P was only expected to brighten to magnitude 15 or so this apparition even though it passed within 0.42 AU of the Earth and 1.41 AU of the Sun in late October/early November. A number of outbursts and splitting events resulted in 168P brightening up to 9th magnitude. Recent large telescope observations have detected a secondary nucleus which split off from the main nucleus during on of the outbursts.
As of the 1st of the month, 168P is probably a little fainter than 10th magnitude as it slowly fades after its last outburst. Hopefully another outburst will occur and push the comet back into the realm of small telescope observation.