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February Skies 2009


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01/29/2009
February Skies -- by Dick Cookman

Highlights: Comet Journal, Martian Landers, Planet Plotting, Meteors, February Moon

Focus Constellations: Ursa Major, Draco, Ursa Minor, Cepheus, Cassiopeia, Perseus, Auriga, Taurus, Gemini

Comet Journal

Comet C/2007 N3 (Lulin) moves rapidly from Libra to Leo in February. It reached 6th magnitude after passing through perihelion on January 15th. By February 24th when it will be closest to Earth (0.41 AU) and near opposition it may exceed 5th magnitude and be visible to the naked eye as it moves through Leo. Its retrograde orbit will cause it to rapidly diminish in brightness as the Earth and comet retreat from one another.

After peaking at 8th magnitude following perihelion in December, Comet 210P/2008 X4 (Christensen) has diminished to 11th magnitude and is no longer visible in binoculars.

Comet 144P/Kushida (2009) passed through perihelion on January 26th when it also peaked at 8th magnitude. It orbited inside of the orbit of Mars in January and will dim as it moves beyond Mars' orbit in February.

Martian Landers

Opportunity has completed reconnaissance of Victoria Crater. After landing, the rover spent a couple of years approaching the crater and then devoted another year for exploration. Opportunity is now heading southward then southeastward towards Endeavour Crater, approximately 16 to 20 kilometers away, farther than the total distance traveled since landing. Scientists decided to devote the next two years to the journey to Endeavour because it is much wider and deeper than Victoria Crater and may reveal more about the ancient past of Mars. Victoria Crater is about the same size as Meteor Crater in Arizona whereas Endeavour Crater is 14 times wider and about 1000 feet deep.

Opportunity has found evidence of past water wherever it’s traveled. The scale of the watery environment that existed in the past far exceeds puddle or ponds. At one time features at least lake-size existed on the planet.

Spirit is on the other side of the planet at a place called Home Plate Plateau which is in the inner basin on the other side of the mountains crossed since landing on Mars. The rover is now coming out of winter and plans include moving south about 300 meters, about three football fields, to search for evidence for hydrothermal systems which appear to exist in this area.

About a year ago Spirit discovered high-purity silica –– good evidence of ancient hydrothermal systems or hot springs on ancient Mars. That’s significant because it means that Mars was more Earthlike and that it had the potential for an environment that could have supported life. Interestingly, Spirit discovered the silica due to its failed wheel, which is one of the only real serious hardware failures either vehicle has experienced. Now when the rover drives, it drags that wheel and cuts a little furrow which unearths material that’s just beneath the surface. This led to the unplanned discovery of opaline silica which is produced by hydrothermal activity.

According to John Callas of JPL, project manager for the rovers, "There are two great questions about Mars. One is was there life on Mars or is there life there today? The rovers have told us that Mars was at one time like the Earth, and provided a potentially habitable environment. The other great question for Mars is why has it changed, why is it so different from the Earth today? What happened to Mars? Why did it lose its atmosphere and its oceans, its surface waters and become a cold, dry, barren planet? What changed about Mars and what does that mean for us?"

Planet Plotting

The morning planets in February are Mercury, Mars and Jupiter. Neptune rises after sunrise in early February and slightly before the Sun at the end of the month. Uranus, Venus and Saturn are evening planets with Uranus and Venus setting in the west within 3 hours of sunset and Saturn dominating the midnight sky after rising at 8 PM.

Mercury is at maximum western elongation when it is 26.1° from the Sun on Friday, Feb. 13th. Venus achieves maximum brightness for 2009 on February 20th as it approaches inferior conjunction when it is between Earth and the Sun on March 27th. In the last half of February, Jupiter starts to brighten as it ascends from the glow of dawn after passing through conjunction with the Sun in January. Saturn also grows more brilliant as it approaches its March opposition when Earth moves between it and the Sun. This brilliance is enhanced as Saturn appears to spread its wings as the rings assume a greater tilt relative to Earth.

Date..Planet.....Constellation..Magnitude.....Planet Passages

2/23...Mercury....Capricornus...-0.1.....Jupiter, 0.6°N, 10 PM EST
2/17...Mars........Capricornus....1.3.....Jupiter, 0.6°N, 5 AM EST
2/17...Jupiter.....Capricornus...-1.9......Mars, 0.6°S, 5 AM EST
2/23...Jupiter.....Capricornus...-1.9......Mercury, 0.6°S, 10 PM EST

Meteors

Sporadic fireballs that often cluster during February partially compensate for the scarcity of February meteor showers. The normal rate of sporadic meteors is about 7 per hour. The February fireballs may result from old untraceable showers that are no longer recognized.

The Alpha Centaurid meteor shower occurs on February 7th, 2 days before Full Moon when glare from the waxing gibbous Moon dominates the sky. The shower emanates from Alpha Centauri in the southern hemisphere sky.

February Moon

The Full Moon of February occurs on the 9th at 9:49 AM EST. It is known as the "Wolf, Snow, or Hunger Moon." It was the "Trapper's Moon" to Colonial Americans and the "Storm Moon " for medieval English. Chinese refer to it as the "Budding Moon", and for the Celts it was the "Moon of Ice". Anishnaabe (Chippewa and Ojibwe) know it as "Namebini-giizis" (Sucker Moon).

Planet....Mag..Constellation.....Moon Passage........Phase/Age

Sun......-26.8..Aquarius..........8:35 PM EST. 2/24...New
Mercury..-0.1..Capricornus..1.1°N, 5 PM EST, 2/22..Waning Crescent
Venus.-...4.8..Pisces..........1.3°S, 6 PM EST, 2/27..Waxing Crescent
Mars.......1.3..Capricornus..1.7°N, 3 AM EST, 2/23..Waning Crescent
Jupiter...-1.9..Capricornus...0.7°N, 8 PM EST, 2/22..Waning Crescent
Saturn.....0.7..Leo.............6.0°S, 3 PM EST, 2/11...Waning Gibbous
Uranus....5.9..Aquarius.......4.3°N, 1 AM EST, 2/26..Waxing Crescent
Neptune..8.0..Capricornus...1.7°N, 9 PM EST, 2/24...Waning Crescent

The penumbral eclipse during Full Moon is centered on the Pacific Ocean and visible from western North America.



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