In The Sky This Month – May 2010
May 1, 2010 9 Comments
This feature highlights a number of meteor showers, comets and asteroids which are visible during the month of May 2010. Venus continues to ascend higher in the evening sky and is the brightest star during early evening hours. The major meteor shower, Eta Aquariids, will be washed out by a bright Last Quarter moon.
Note: If anyone has pictures or observations of these objects/events and want to share them, send me a comment and I’ll post them on the blog.
Venus – Venus is the brilliant star low in the west during the early evening hours. It sets about 2 and half hours after the Sun. Venus will only get a little higher next month. From now till July/August it will ride as high as it’ll get for this apparition for northern observers. In fact, this is not a very good evening apparition for Venus. On the other hand, it is a great apparition for observers south of the Equator. For you, Venus will continue to climb till late August.
May 16 - Moon passes within 0.6° from Venus
Mars – This month the Earth and Mars continue to move further apart. As a result, Mars will continue to fade from magnitude +0.7 to +1.1. Still it will be a bright red beacon nearly overhead right after sundown. It’s brightness is comparable to that of the other bright stars. Note that unlike the stars which twinkle, Mars shines with an unwavering red glow.
May 20 - Moon passes within 5° of Mars
Saturn – Saturn was at opposition in Virgo on March 21. This month Saturn is visible in the east-southeast during the early evening hours. It will slowly fade from magnitude +0.8 to +1.0 throughout the month. Telescope users should note that Saturn’s rings are still within a few degrees of edge-on.
May 22 - Moon passes within 8° of Saturn
Jupiter – Jupiter once again returns to sight as a brilliant star low in the east-southeast before dawn. The magnitude -2.2 planet will get brighter and better place for observing over the next few months.
May 9 - Moon passes within 6° of Jupiter
Mercury -Mercury will rise out of the dawn sky toward the end of the month. This morning apparition will not be good for northern observers.
May 12 - Moon passes within 8° of Mercury
May starts to see an increase in meteor activity after a few months of low activity. The year is usually split in 2 with January through June having low rates with few major showers while July through December (really through the 1st week of January) have high rates with many major showers.
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 May, 10-12 or so Sporadic meteors can be observed per hour from a dark moonless sky.
Major Meteor Showers
Eta Aquariids (ETA)
The Eta Aquarids are a major shower, especially for southern hemisphere observers, when they peak on May 5. For northern observers, the shower will only be observable for an hour or two before dawn. Since the radiant doesn’t get very high for NH observers, rates can be low. The radiant is located near the “jar” of Aquarius.
The ETA were produced by Comet Halley which also gives us the Orionids in October. Models suggest that the ETA were released by Comet Halley no later than 837 AD. The Orionids are easy to see because the particles are hitting the Earth from the anti-solar direction. This means the meteor shower can be seen in the middle of the night. The ETA are produced by meteoroids moving outbound from the Sun, as a result the radiant is located relatively close to the Sun. This means that the ETA radiant is only visible for an hour or so before twilight. By luck, the nearly Full Moon will have just set making the last hour of the night dark.
The shower spans from April 19 to May 28 with a peak around May 5 with a maximum ZHR of ~60.
Additional information on these showers and other minor showers not included here can be found at the following sites: Robert Lunsford’s Meteor Activity Outlook.
Minor Meteor Showers
Minor showers produce so few meteors that they are hard to notice above the background of regular meteors. Starting this month, info on most of the minor showers will be 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 following sites: Wayne Hally’s and Mark Davis’s NAMN Notes, and the International Meteor Organization’s 2008 Meteor Shower Calendar.
Naked Eye Comets (V < 6.0)
Binocular Comets (V = 6.0 – 8.0)
Comet C/2009 R1 (McNaught)
There are 2 comets bright enough to be seen in small telescopes this month. Both were discovered by Rob McNaught of Australia during the Siding Spring Survey. As a result, both comets go by the moniker of Comet McNaught though they do have different designations [Comet C/2009 K5 (McNaught) and Comet C/2009 R1 (McNaught)].
The comet that should end the month as the brightest is Comet C/2009 R1 (McNaught). This comet was found on Sept. 9, 2009 with the 0.5-m Uppsala Schmidt telescope from Australia. At the time, the comet was a faint 17th magnitude.
Perihelion will be on July 2nd of this year at a relatively small distance of 0.41 AU from the Sun. This month it will be 1.44 AU from the Sun and 1.96 AU from Earth on May 1st, 1.19 AU from the Sun and 1.61 AU from Earth on the 15th, and 0.90 AU from the Sun and 1.28 AU from Earth on the 31st. Currently the comet is around magnitude 10.0 and should brighten to ~7.0 by the end of the month. 10th magnitude requires a small telescope but under dark skies while 7th magnitude should be easy for small telescopes under most sky conditions and binoculars under a dark sky. It is a morning object as it moves from Pisces, through Pegasus and into Andromeda.
This comet may even brighten to naked eye brightness (under very dark skies) in June. Of course with relatively small comets getting this close to the Sun, there is always a chance the comet will break up and disintegrate before it gets too bright (as C/2009 O2 did last month).
A finder chart for Comet McNaught can be found at Comet Chasing.
Small Telescope Comets (V = 8.0 – 10.0)
Comet C/2009 K5 (McNaught)
The 2nd ‘Comet McNaught’ is Comet C/2009 K5 (McNaught). It was discovered on May 27, 2009 deep in the southern sky. Similar to C/2009 R1, this comet was also found with the Uppsala schmidt at around magnitude 17.
With perihelion on April 30 of this year at a distance of 1.42 AU from the Sun, C/2009 K5 is bright enough to be seen in small backyard telescopes from dark sites. During the month it should be as bright as it gets at around magnitude 8.2 to 9.0. The comet will move through Cepheus and Camelopardalis. As the month progresses, the comet will have traveled far enough north to be circumpolar and visible all night long (for observers at northern mid-latitudes and further north). At mid-month it will be located 1.44 AU from the Sun and 1.51 AU from Earth.
A finder chart for Comet McNaught can be found at Comet Chasing.
Binocular and Small Telescope Asteroids (V < 9.0)
Vesta is the brightest asteroid in the Main Belt. This is due to its high albedo (or reflectivity) which causes it to reflect ~42% of the light that strikes it. Vesta is also peculiar in that it appears to have evidence of volcanism on its surface. Similar to the Moon, Vesta may be covered with large expanses of frozen lava flows. It is classified as a V-type asteroid and is the only large asteroid with this classification. Many of the smaller V-type asteroids are chips of Vesta blasted off it by past asteroid and comet impacts. Vesta has dimensions of 347x336x275 miles or 578×560×458 km.
The maps below were created from images taken with the Hubble Space Telescope. The geography is dominated by a large impact crater located near the south pole (the blue ‘donut’ in the elevation map). Perhaps this crater is the result of the impact that blasted off the smaller V-type asteroids. We’ll know more next year when NASA’s Dawn spacecraft enters orbit around Vesta for a full year. Currently the encounter is scheduled for July 2011 to July 2012.
Vesta starts the month at magnitude 7.3 and steadily fades to mag 7.7. A small pair of binoculars will allow you to see Vesta among the stars of Leo.
Pallas is a dark carbonaceous asteroid though with a slightly bluish B-type spectrum. Due to its high inclination (tilt of its orbit with respect to Earth’s orbit) of 34 degrees it is a difficult target for future spacecraft missions. Pallas is similar in size to Vesta with dimensions of 350x334x301 miles or 582x556x501 km. The reason it is fainter than Vesta is its darker albedo of 16%. Though no spacecraft are scheduled to visit Pallas, Hubble was able to get some good images that clearly show its nearly spherical shape.
This month it fades from magnitude 8.7 to 9.0. Over the course of the month it travels north from the constellation of Serpens Caput into Corona Borealis.