TSTW 1/19/12
Thursday, January 19
The 18.8-magnitude unnamed asteroid 29156 (1989 CH) may pass in front of the 8.2-magnitude star HD 10508 in Cetus for up to 0.4 seconds around 7:44:24 p.m.
Algol (β Persei) is at minimum brightness around 11:15 p.m.
Friday, January 20
The Moon rises at its most southerly point along the eastern horizon this month at 5:25 a.m.
The Iridium 31 satellite will sunglint to -4 magnitude around 7:03:41 p.m. at azimuth 41° (NE) and altitude 62°, between Perseus and Capella, during nautical twilight.
The 19.3-magnitude asteroid 4180 Anaxagoras may pass in front of the 10.4-magnitude star Tycho 0024-00446-1 in Pisces for up to 0.4 seconds around 9:22:42 p.m.
The Great Red Spot crosses Jupiter's central meridian around 9:23 p.m.
Saturday, January 21
Gamma Ursae Minorid meteors may be seen around this date (2 meteors per hour, or less; circumpolar radiant transits at 8:09 a.m.).
Io reappears from Jupiter's shadow around 7:51 p.m.
Ganymede disappears into Jupiter's shadow around 10:01 p.m.
Ganymede reappears from Jupiter's shadow around 11:51 p.m.
Sunday, January 22
Jupiter is at east quadrature (90° east of the Sun) and thus exhibits its most gibbous phase (99.0% illuminated), around 1:00 a.m.
The 13.2-magnitude asteroid 207 Hedda may pass in front of the 12.8-magnitude star 2UCAC 36825431 in Leo for up to 11.8 seconds around 5:41:00 a.m. For more information, visit http://asteroidoccultation.com/asteroid.htm.
Pierre Gassendi (1592-1655), French philosopher, astronomer, and mathematician who observed and published high quality observations of the first-observed transit of Mercury (1631), was born 420 years ago.
Algol (β Persei) is at minimum brightness around 8:05 p.m.
The Great Red Spot crosses Jupiter's central meridian around 11:02 p.m.
Monday, January 23
The 14.6-magnitude asteroid 606 Brangane may pass in front of the 12.2-magnitude star 2UCAC 35028044 in Leo for up to 3.3 seconds around 6:24:28 a.m. For more info, visit http://asteroidoccultation.com/asteroid.htm.
New Moon; rises 7:51 a.m.; transits 1:26 p.m.; sets 7:07 p.m.; δ = -16°; 3.6° from the Sun at 1:44 a.m.
Cosmos 2219 rocket body (N to SE) - 8:03:14 p.m. crosses the handle of the Little Dipper; 8:06:30 Auriga; 8:07:56 Betelgeuse; 8:08:42 disappears into the shadow of the Earth in Orion; 2.1m, 58°
The 18.0-magnitude asteroid 18263 Anchialos may pass in front of the 9.9-magnitude star BD +16° 1907 in Cancer for up to 1.2 seconds around 8:32:36 p.m.
Tuesday, January 24
Mars begins retrograde (westward) motion relative to the background stars in Virgo at 12:45 a.m.
What the hey, Mars resumes prograde (eastward) motion relative to the background stars at 9:23 a.m.?! What's up with that?? Hint: topocentric phenomenon.
Harold Babcock (1882-1968), American astronomer and eminent spectroscopist, was born 130 years ago.
Mars resumes retrograde (westward) motion relative to the background stars at 10:02 p.m.
Wednesday, January 25
NASA formally assigned the task of developing the Saturn V moon rocket to the Marshall Space Flight Center near Huntsville, Alabama, 50 years ago (1962).
Mars resumes prograde (eastward) motion (again!) relative to the background stars at 12:39 p.m.
The Progress M-14M (46P) robotic cargo ship is scheduled to launch at 5:06 p.m. from the Baikonur Cosmodrome, Kazakhstan, on a mission to the International Space Station.
Mars resumes retrograde (westward) motion (this time for good) relative to the background stars at 7:08 p.m.
Venus is near the Moon this evening and tomorrow evening.
The Great Red Spot crosses Jupiter's central meridian around 8:33 p.m.
Normally, Mars moves slowly eastward from night to night relative to the background stars. But like two racecars going around a racetrack, when Earth (the inner, faster car) is overtaking Mars (the outer, slower car), Mars for a time appears to be going backwards. This is called retrograde motion.
From January 25 through April 15, Mars will appear to move backwards, or westward, relative to the background stars. This in combination with the stars rising 4 minutes earlier every night due to the Earth's orbital motion about the Sun means that Mars will rise significantly earlier each night.
For example, on January 25th Mars rises in the east at 9:58 p.m. and is 15° above the horizon by 1:26 a.m. By this time next month (February 25th), Mars rises at 7:25 p.m. (even before it is completely dark) and is 15° above the horizon by 8:38 p.m.
Mars currently sports a respectable visual magnitude of -0.2, and it's brightening by 0.2 magnitudes per week. When Earth and Mars are closest on March 5, the Red Planet will be an unmistakable beacon shining at visual magnitude -1.2—almost as bright as Sirius. Mars, which this year is in Leo, will outshine Leo's lucida Regulus by eleven times, though it will appear only about three times as bright due to the pseudo-logarithmic response of the human eye.
French philosopher, theologian, astronomer, and mathematician Pierre Gassendi was born 420 years ago this week. In 1631, at the age of 39, Gassendi observed the planet Mercury crossing in front of the Sun (called a transit). The great astronomer Johannes Kepler (1571-1630) had predicted the event so accurately that there could now be no doubt that the heliocentrism espoused by Nicolas Copernicus nearly a century earlier was correct: the Sun is at the center of the solar system, not the Earth. Gassendi's observation of the transit of Mercury (the first ever observed) may well have been the defining moment when Copernicus' sun-centered model of the solar system went from theory to fact. Sadly, Kepler had died the previous year and could not enjoy the success of his exquisite prediction.
In his posthumously published lecture notes, Syntagma philosophicum (1658), Gassendi was perhaps the first to suggest that at least some of the nebulae seen in the sky at night might be other galaxies like the Milky Way, but he then dismissed the idea as fanciful speculation.
Gassendi had other astronomical accomplishments. In 1621, he described the northern lights, and in that description was the first to use the term aurora borealis.
A prominent flooded crater on the northern edge of Mare Humorum in the southwest quadrant of the Moon (SE on the sky) is named after him.
• The McDonald Observatory Exoplanet Program was initiated by Bill Cochran and uses the Robert G. Tull Coudé spectrograph on the 2.7 m Harlan J. Smith Telescope to detect the radial velocity variations of stars that are gravitationally influenced by orbiting exoplanets. The High Resolution Spectrograph (HRS) on the 9.2 m Hobby- Eberly Telescope (HET) has been a very productive addition to this effort. In addition to various exoplanet survey projects, these instruments are also used to follow up on Kepler mission discoveries—either confirming or weeding out false positives. HET is now yielding radial velocity measurements with a precision of 5 to 7 meters per second.
• For dwarf (main sequence) stars, there is a definite trend towards higher metallicity stars being more likely to have planets. This trend is not observed for giant stars.
• Radial velocity "jitter" of ~20 m/s for early giants and ~50 m/s for later giants is making the detection of smaller planets around giant stars much more difficult. The mechanism causing this jitter is not yet well understood, but non-radial and radial oscillations are probably a factor.
• Lower metallicity giants have more jitter, and higher metallicity giants less jitter, and yet we're not detecting as many exoplanets as expected around these higher metallicity giants.
To be continued...
