Winter has finally caught up with us, so we should be prepared for some long, cold nights this month. There are two highlights this February, the opposition of Saturn and Mercury's greatest elongation from the sun.

Saturn will reach opposition on Saturday, Feb. 10. It will be opposite the sun in our sky, which means that it will rise as the sun sets and that it will remain in our sky all night long. It will reach its highest point in the sky of around 30 degrees up at local midnight. After that it will start rising before sunset and reach its highest point before midnight.

The best time each year to look at a superior planet (one that orbits the sun outside of Earth's orbit) is at or near its opposition. The planet is closest to Earth and at its brightest, largest and highest in the sky for the year at that time. Saturn will be 762 million miles away, which is just over one hour at the speed of light, which travels at 186,000 miles per second, or 670,616,629 miles per hour.

Saturn shines with a steady, golden light at zero magnitude in the constellation of Leo the Lion and covers 20.3 arc seconds of the sky. The tilt angle of its rings is decreasing now, and it will appear to have no rings at all for a while in 2009. The last time Saturn looked like it had lost its rings was in 1996.

You can easily see its largest moon, named Titan, through a telescope. You may also be able to see four more of its 47 current moons through a good backyard telescope. These are Tethys, Dione, Rhea, and Enceladus, whose recently discovered ice geysers provide the particles that make up the E-ring around Saturn.

We learned a great deal more about Titan two years ago, when the Cassini mission dropped the Huygens probe onto its surface. Titan is the only moon in our solar system with a dense atmosphere, about 10 times as dense as ours.

Rich in organic material, Titan resembles the Earth of about 3 billion years ago, before oxygen was introduced into our system by bacteria that could photosynthesize the sun's energy to make sugars.

Landing on a gravelly outflow wash on the distant, alien shores of a dried lakebed with rounded ice pebbles in a steady drizzle of methane at 290 degrees below zero, the Huygens probe saw a surprisingly dramatic landscape of channels formed by some kind of flowing liquid, probably methane or ethane. Cryo volcanoes erupt occasionally on Titan, releasing the trapped heat of its still active interior. They are still analyzing data from this mission, and the orbiting Cassini mission will gather more data about Saturn and its moons for another two years, solving more mysteries about these enigmatic and distant worlds.

Our first planet, Mercury will reach greatest eastern elongation from the sun at 18 degrees on Feb. 7. It will be visible about 7 degrees below and to the right of Venus in the western evening sky about 40 minutes after sunset. Called inferior planets, since they orbit inside of Earth's orbit, both Mercury and Venus go through phases like the moon. They are both nearly full, in a waning gibbous phase early this month, but Mercury changes faster and will be reduced to a thin sliver in the waning crescent phase by the middle of this month. Venus, at minus 3.9 magnitude is 3 magnitudes, or nearly 16 times brighter than Mercury at minus 0.9 magnitude.

Mercury is a very interesting little planet that still harbors many mysteries. Not that much is known about our first planet, since we have only sent one mission there, Mariner 10 back in 1974. However, another mission called Messenger was launched on Aug. 3, 2004, and will swing by Mercury in 2008 and 2009, but will not settle into its orbit until March 2011. This spacecraft will tell us many new things about this puzzling planet, including why it has such a high density, its geologic history, the nature and cause of its weak magnetic field, the structure of its core, and where its tenuous atmosphere came from.

Mercury is only 3,000 miles in diameter, which is smaller than two of the moons in our solar system, Ganymede around Jupiter and Titan around Saturn. Because it is the closest planet to the sun, Mercury orbits at the fastest speed of any of our eight planets. It orbits at around 30 miles per second, compared with 18.6 mps for Earth and 5 mps for Pluto, which was demoted to an icy dwarf planet last summer.

That rapid revolutionary speed around the sun makes one year on Mercury last only 88 days. The strange thing is that it rotates so slowly that one day equals 59 Earth days. That locks it into a 3 to 2 ratio, doing only three rotations for every two orbits around the sun. If you could walk around on Mercury, you could actually see the sun rise about half way up, then reverse itself and set before rising again, all in the same Mercurian day.

The coldest it gets on Mercury on the side away from the sun is minus 300 F, which is as cold as Titan, nearly 1 billion miles from the sun. The hottest it gets is 800 F on the side facing the sun, which is as hot as all of Venus always is, due to its thick atmosphere and runaway greenhouse effect.

Jupiter and Mars are still the morning planets and they continue to climb a little higher into our sky each morning.

Feb. 2. Full moon is at 12:45 a.m. EST. This is also called the Hunger, Snow, Storm, or Wolf Moon. The moon passes just one degree north of Saturn this evening. Feb. 3. On this day in 1971, Apollo 14 landed on the moon. This was the third of six lunar landings and the last one that did not use a lunar rover. Feb. 4. Clyde Tombaugh was born on this day in 1906. He discovered Pluto on Feb. 18, 1930. Feb. 7. The moon is at apogee, or farthest from Earth for the month at 251,651 miles. Feb. 10. Last quarter moon is at 4:51 a.m. Saturn is at opposition. Feb. 12. Jupiter is 6 degrees north of the moon this morning. Feb. 14. The slender waning crescent moon passes 4 degrees south of Mars this morning. Feb. 15. Galileo was born on this day in 1564. He discovered many amazing things with his early telescopes in 1609 and 1610 that we now take for granted. These include the four largest moons in their constant orbits around Jupiter, the rings of Saturn, sunspots, craters on the moon, and many more discoveries. Feb. 17. New moon is at 11:14 a.m. Feb. 19. The moon is at perigee at 224,586 miles from Earth. The waxing crescent moon passes 2 degrees north of Venus this evening. Nicholas Copernicus was born on this day in 1473. He was the Polish priest who developed the heliocentric theory stating that all the planets orbit the sun. That was later proven by Galileo, but not acknowledged until later. Feb. 24. First quarter moon is at 2:56 a.m. Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England.