What can astronomy enthusiasts look forward to in the upcoming year? Here are some events, due to the motions of solar system bodies, that could have been predicted a century before now. Here also are events due entirely to human ingenuity that would have been thought possible only by the most far-sighted dreamers of 1912. A robot landing on Mars and then rolling off to explore the landscape! Another robot leaving orbit around one asteroid and setting out to explore a second one! We truly live in an age of wonders. But then we always have, for as long as we have looked up at the sky.
The World Won’t End In December
If you enjoy watching an “astronomy person” grit her teeth or try really, really hard to be polite and not to roll his eyes, just ask him or her about the end of the Mayan calendar and the end of the world in December 2012. AARRGGHH!! If you want the truth (and some folks just can’t handle the truth; thank you, Jack Nicholson), there is a web page from NASA that provides it.
Or you can just watch the movie. No, not THAT movie!
Is The Moon Up Tonight?
So much of what you can see in the sky depends on the phase of the moon. The full moon is in the sky all night, and it is really bright! Meteor showers will be less obvious if the moon is bright, and the full glory of the Milky Way is washed out unless the night is moonless. So here is your handy moon phase calendar generator, so you won’t have to guess.
A quick guide to when various moon phases rise and set:
Waxing crescent: low in the west after sunset; sets early in the night.
First quarter: high in the south at sunset; sets around midnight.
Waxing gibbous: in the southeast at sunset and in the sky most of the night.
Full moon: rises at sunset and sets at sunrise; in the sky all night.
Waning gibbous: rises a little after sunset and sets a little after sunrise
Last (or third) quarter: rises at midnight and sets at noon.
Waning crescent: only visible at night in the early morning hours before dawn.
New moon: not visible, although it rises and sets with the sun.
Here are the most easily seen showers—not a comprehensive list. I’ve given the days and times as the night you need to stay up to try and avoid confusion. All the times before midnight are on the earlier date; those after midnight on the later date, and are for the Eastern time zone.
Tuesday/Wednesday, January 3rd/4th: Quadrantids. The moon will be in a waxing gibbous phase, but when it sets around 3:20 a.m., you should get some good viewing in. The forecast temperature for Lynchburg of 19° F means only the truly dedicated will be watching!
Saturday/Sunday, April 21st/22nd: Lyrids. A new moon means conditions are near-perfect. Peak should be around midnight.
Saturday/Sunday, August 11th/12th: Perseids. These are everyone’s favorite meteors, because the weather is seldom severe. The waning crescent moon (actually pretty close to last quarter) rises around midnight but shouldn’t be too much of an interference.
Saturday/Sunday, October 21st/22nd: Orionids. Meteor showers are associated with comets that leave debris strewn all along their orbits. When the Earth crosses the orbit, that debris enters our atmosphere and creates “shooting stars”. The Orionids are due to the famous Halley’s Comet. The moon will set around midnight.
Sunday/Monday, November 11th/12th: Taurids. These meteors are famous for producing fireballs! I observed one myself one Halloween night that was really impressive—it was as though someone had fired off an old-fashioned flash bulb in my face. It left a smoke trail that was visible for several minutes. There is an earlier peak at the end of October (hence my Halloween experience), but the full moon will interfere with that in 2012. The moon will be new by the date given here, however.
Friday/Saturday, November 16th/17th: Leonids. The moon sets around 8 p.m., so will not interfere.
Wednesday/Thursday, December 12th/13th: Geminids. New moon for the peak! This shower gives fairly predictable rates of around 100 per hour, one of the best there is.
Meteors from these showers are generally seen both before and after the dates given, although they do peak on these dates. Although meteors in a given shower all appear to emerge from a point in the sky (the “radiant”), this is an optical illusion. They follow parallel paths to the Earth, and their paths appear to converge for the same reason that parallel railroad tracks do. But they will appear all over the sky, and the best viewing tip is simply to lie flat, make yourself comfortable, and look up.
Lunar eclipses can only occur when the moon is full, and can be seen anywhere on Earth if the moon is visible. The Earth is between the sun and the moon, and its relatively large shadow falls on the moon.
Solar eclipses can only occur when the moon is new. The moon is between the Earth and the sun, and since it is much smaller than the Earth, its shadow does not fall on all the Earth’s surface. A total solar eclipse is visible (if at all) only along a narrow strip, while partial phases (where the moon covers some, but not all, of the sun) are seen along either side of this central path.
Lunar eclipses do not occur with every full moon, and solar eclipses do not occur with every new moon. The two bodies must line up as seen from Earth for an eclipse to be seen.
Complicating this (and leading to total solar eclipses of varying duration) is the fact that the apparent sizes of the moon and the sun as seen from Earth are very close to the same. The moon is 400 times smaller but it is also 400 times closer. If they were exactly the same, of course, totality would last for only an instant. But the moon’s path around the Earth is elliptical, and sometimes it is closer and therefore appears larger. If a total solar eclipse were to occur when the moon is nearer the Earth, the duration of totality from a given spot on Earth would be longer. Conversely, if the eclipse occurs when the moon is farther from Earth (and therefore appears smaller), it would cover only the central part of the sun, and leave a “ring of fire” around the edge of the moon’s disk. This is an annular eclipse, and there will be one of these in 2012.
For those of us in the eastern U.S., 2012 is not a year for eclipses, unless we travel!
Lunar Eclipses: Partial eclipse on June 4th, visible before dawn in central and western US.
Penumbral eclipse on November 28th, most visible in Pacific states and west before dawn. A penumbral eclipse is one where no part of the moon’s surface is entirely shaded from the sun by the Earth. But part of the moon will be partially shaded by the Earth. In other words, part of the full moon will be slightly less bright than the rest. You will probably have to look closely to notice it.
Solar Eclipses: Annular, evening of May 20th. The sun will set while eclipsed in some places (Mountain time zone) and the entire eclipse will be visible in others (Pacific time zone). The sun will be higher in the sky during eclipse as one goes farther west—a point in the Pacific just southwest of the Aleutian Islands would be an ideal location for viewing it, except for the likely cloud cover.
Total: November 14th in eastern Australia, just after sunrise. Maximum eclipse in open Pacific Ocean, duration 4 minutes.
Planets In The Night Sky
Mercury: This closest planet to the sun is hard to spot because of that very proximity. From our point of view, it never appears more than 28° away from the sun, usually less. Your fist at arm’s length is about 10° wide.
How good a viewing opportunity we get depends on how far Mercury swings from the sun (which varies because of Mercury’s elliptical orbit) and the angle the sun and Mercury make with the horizon. The two best opportunities to glimpse Mercury with your naked eye will come just after sunset in early March, and just before sunrise in early December.
Venus: Venus is currently the bright “evening star” in the southwest, rising ever higher (farther from the sun) each night and reaching its maximum elongation from the sun in late March. It then begins its descent toward an historic transit of the sun on June 6th (see below). It emerges into the morning sky a few days later, and spends the rest of 2012 as a “morning star”.
Mars: Mars reaches opposition on March 3rd. This is the point when it is exactly opposite the sun in our sky, and the sun, Earth and Mars make a straight line as shown below:
This is when it is nearest to us, and therefore brightest, although just how near varies, once again because of an elliptical orbit (Mars’). This opposition is one where Mars is not all that close to us compared to others. Mars is notably ruddy-colored (more orange than red), and as it gets brighter early in the year, this will be even more obvious. Look for Mars above the full moon on the night of March 7th.
Jupiter: The largest planet in our system begins the year high in the south in the early evening, slowly moving a little to the west on each successive night. In May, it is invisible, behind the sun from us. It comes back into view in the early morning in a couple of weeks, and on July 1st it will pass within 5° of Venus before sunrise. Starting in September it is again an evening sight, and on December 3rd, Jupiter will be at opposition. A planet at opposition is highest in our southern sky at midnight.
Saturn: The ringed planet is currently an early morning sight, rising about 1:40 a.m. in early January. But that rising time gets a little earlier every night, and by the time pleasant weather arrives in May, it will be visible in the east after sunset. It should be a great sight all summer before it disappears behind the sun in October.
In 1882, then again in 2004, Venus passed across the face of sun, an event known as a transit. It will do so again in 2012, then not again until 2117. Unless you have some secret longevity formula, this is your last chance.
These events are as rare as they are predictable. Two transits, separated by eight years, occur at intervals of 130 years. The 1882 transit was preceded by one in 1874, and the 2117 event will be followed by one in 2125.
From the U.S., the transit begins at the end of the day, and the sun sets before it is over. The safest way to see this is with a pinhole in a card, held in front of a large white card. Adjust the distance between the two until you see a sharp image. If you want to get a little fancier, you can use a shoebox as shown here:
The entire transit from start to finish will be visible from Alaska and Hawaii, northwestern Canada, northern areas of Europe, most of China, Japan, eastern Australia, and essentially all of the Pacific Ocean. The map below shows the global zones of visibility.
SpaceCraft Launches And Rendezvous
Finally, what about our robot solar system explorers? Here is a rundown of some upcoming highlights:
In July, the Dawn mission will complete its survey of the asteroid Vesta and will depart for Ceres, the largest asteroid. It will arrive at Ceres in 2015.
The Curiosity rover will be landing (softly, we hope!) on Mars just after midnight on August 6th. The rover is too big and heavy to land with airbags as the Spirit and Opportunity rovers did in 2004. Here is a great animation showing the frighteningly complex sequence of events required to land the rover safely, from low Earth orbit to successful touchdown to beginning its scientific mission:
Its landing site on Mars is Gale Crater, whose central mountain shows layered rocks that look intriguing. The nuclear-powered rover will have plenty of energy to explore extensively; it won’t be dependent on solar cells that provide less power in the winter and get progressively more dusty as they continue to operate. Here is Gale Crater and the landing ellipse for Curiosity.
There are no other planetary missions scheduled to launch or rendezvous this year, but the Cassini orbiter at Saturn will complete several very close (less than 50 miles) flybys of the ice moon Enceladus. Enceladus surprised us all with its ice fountains, captured beautifully in this image.
Save this post! I wish you all clear skies and happy viewing in 2012.