Thursday, December 31, 2015

Tonight's Sky for December 31: Get Sirius for the New Year

Ring in the New Year with Sirius, alpha (brightest) star of Canis Major, the big dog, and brightest star in the entire sky. Why the New Year connection? Sirius is very near to due South on New Year's Eve. To see it, go out at midnight and look South to find an extremely bright blue star, Sirius. 

Wednesday, December 30, 2015

Tonight's Sky for December 30: Venus Rises 3 Hours Before the Sun

This morning, Venus, second planet from the Sun and third brightest object in the night sky, will be rising 3 hours before the Sun. Now, while not as early as the 4 hours before the Sun rise that was taking place last month, any morning planet rising 3 hours before the Sun mean t hat it will still be pretty high come the predawn hour. 

Tuesday, December 29, 2015

Tonight's Sky for December 29: Mercury at its Best


Want to join a small club of people who have seen the planet Mercury? Well, here's your chance as the first planet from the Sun has reached a point in its orbit called greatest elongation, which is a fancy way of saying that, as seen from Earth, Mercury is as far from the Sun as it will get on this orbit, which is crucial for observing as, of all the Classical Planets (those known to the Ancient Greeks and Romans), Mercury is by far the hardest to spot because, as seen from Earth, it spends a lot of time obscured from view by the Sun's glare.


So, take a moment or two, go out just after sunset, and try to spot Mercury. If you are successful in spotting the speedy planet, you are accomplishing something that the great astronomer Nicolaus Copernicus (who rediscovered the idea of a sun-centered solar system) supposedly never did. 

Monday, December 28, 2015

Tonight's Sky for December 28: Orion Due South at Midnight

Tonight, Orion, king of the winter sky, is due South at midnight. For anyone just getting into astronomy who wants to see one of the most famous constellations in the sky, here's a perfect opportunity to do do.

Sunday, December 27, 2015

Tonight's Sky for December 27: Johannes Kepler Born (1571)


It was on this date that Johannes Kepler was born. Initially sent to a seminary to become a member of the Lutheran Clergy, Kepler instead found a love for mathematics, which became his first profession when he took a job as a math teacher. While a teacher, Kepler wrote a book on astronomy, specifically planetary orbits. This work attracted the attention of many astronomers, including Tycho Brahe, the greatest of the pre-telescopic astronomers, who invited Kepler to join his staff.

The relationship between the two men was awkward. Brahe was an astronomer, not a mathemitician, and he knew that he needed Kepler's mathematical genius to make sense of his volumes upon volumes of data. At the same time, Kepler knew he needed Brahe's data if he were to make any discoveries about planetary orbits. Unfortunately for Kepler, Brahe regarded his observational data as his life's work and wasn't about to start giving it out freely. Between the time he joined Brahe's staff in 1599 to the time Brae died in 1601, Kepler almost quit his position several times over frustration about not being granted access to the volumes of data Brahe had compiled in over 30 years of observations.
After Brahe died, though, Kepler would be appointed to Brahe's position of Imperial Mathemitician, which thus granted Kepler access to all of Brahe's data.

Eagerly plunging into his work, Kepler immediately came across problems, specifically that the observational data could not be reconciled with planets having a circular orbit, as proposed by Copernicus. In the time that followed, Kepler tried various models for planetary movement in the hope of finding one that would fit the observations. Try as he might, Kepler just couldn't reconcile the models to the observations, especially in regards to the planet Mars, which exhibited the greatest irregularity in its orbit.. Finally, in desperation, Kepler, a deeply religious man who sought to find proof of a divine blueprint for the solar system, gave up the perfect circles that had so dominated astronomy for centuries. Upon calculating the orbits of the planets as ellipses (slightly elongated circles) the observation and theory finally agreed. It was this discovery that planets' orbits ere elliptical that inspired Kepler's 3 laws of planetary motion.
Law 1: All planets move in elliptical orbits with the Sun at one of the foci.
Law 2: All planets move through equal areas of space in equal times ()basically, planets move faster when closer to the Sun and slower when farther away).

Law 3: A planet's period of orbit is proportional to its distance (orbital period (in years) of the planet squared equals the semimajor axis (in AU) cubed). This discovery showed that there was some common force governing planetary motion (this force is gravity, but Kepler didn't know this yet).



Unfortunately, try as he might, Kepler, while he could explain “hows” of planetary motion, he couldn't explain the “whys.” This task would occupy him for the rest of his life until 1630.

Saturday, December 26, 2015

Tonight's Sky for December 26: Mary Somerville is Born (1780)

It was on this date in 1780 that Mary Somerville, one of the first women to become famous in the field of astronomy, was born.

Somerville's tale is one of struggle against adversity. At the time, girls were not only often denied access to an education, but were often discouraged from seeking one. Mary's situation was no different and her parents even blamed her quest for knowledge for the death of her own sister! While giving up on formal education and taking the societal path of a well-connected lady (her father was a doctor), Mary continued to study in secret and, with the inheritance she got upon the death of her husband, she was free to pursue intellectual interests, with the support of her second husband, eventually becoming known as both a writer and translator.


She was also one of the first women to be inducted into the Royal Astronomical Society, which she achieved in 1835, the same year that Caroline Herschel, William Herschel's sister and assistant, received the same honor. In 1868, Somerville was awarded the Victoria Cross of the Royal Geographical Society.

Somerville died in 1871, aged 91.

Friday, December 25, 2015

Tonight's Sky for December 25: Full Moon

Tonight, the Moon will reach its full phase, which means that, as seen from Earth, it is directly opposite the Sun in the sky as seen from Earth and is at the half way point in its current orbit.


As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, when the Moon is opposite the Sun and on the far side of Earth, we can see all of its lit side, which is why it appears to be “full.” In the coming nights, we will start to see less of the Moon as its lit side starts to turn away from us as seen from Earth and heads toward Third Quarter. 

Tuesday, December 22, 2015

Tonight's Sky for December 24: Apollo 8 Reaches the Moon, Christmas Broadcast

It was on this date that Apollo 8 reached the Moon, becoming the first manned mission to enter into lunar orbit. In addition, this mission featured the famous Christmas Eve Broadcast. Rather than describe this, here's the complete audio.

Tonight's Sky for December 23: Moon Meets the Bull

Tonight, the Moon will be in a very unique place: right on the head of a cosmic bull. Tonight, the Moon will move directly into the Zodiac constellation of Taurus the bull, more specifically, into its head.

To see the sight, go out and look East. The Moon, of course, will be impossible to miss. Moon found, look for a sideways 'V' of stars (set off by bright orange Aldebaran), the Hyades star cluster, which represent the base of the bull's head. Extending the lines of the 'V' out, you will run into a pair of stars of roughly 2nd magnitude (though on opposite ends of the scale) that signal the end of the horns.


Cosmic picture realized, there's the Moon, smack in the middle. 

Tonight's Sky for December 22: The Winter Solstice


Today marks the Winter Solstice, the shortest day of the year for us living in the Northern Hemisphere and the official start of the summer season.

So, why do we have seasons, anyway?

It's all about Earth's tilt. If the Earth were spinning on its axis with no tilt at all, everyone would be treated to days of identical length every day of the year, with latitudes nearer the equator having longer days than those nearer the poles. However, with the tilt, the angle of the Earth relative to the Sun changes as or planet moves about its orbit. On the Winter Solstice the Northern Hemisphere is tilted up and away from the Sun. On the Summer Solstice, the Northern Hemisphere will be tilted down toward the Sun. On the equinoxes, the tilt is half way between the solstices. To see this effect, go out and observe the path the Sun takes through the sky for the course of day of a year.


Monday, December 21, 2015

Tonight's Sky for December 21: Ursid Meteors Peak

Tonight will mark the peak of the Ursid Meteor shower for 2015, thus marking the climax for the 2-week event. Every December, Earth passes through the stretch of space junk shed by Comet NAME, reaching the deepest concentration of debris tonight. According to some estimates, under ideal conditions (dark country skies), one can expect to see 10-15 meteors per hour. The reason the meteors are called Ursids is because the meteors seem to radiate from the constellation Ursa Major (the Great Bear), which contains the famous Big Dipper. The best time to view the shower is in the predawn, as Ursa Major is at its highest then.

Don't want to stay up that late? Don't worry, Ursa Major is circumpolar and is up all night. However, unless one lives out in the country, the early night hours will probably involve Ursa Majr being low in a light dome. To improve odds of seeing meteors, travel out of the city and to the country if you can. In the suburbs, just going from the front to back yard can make a dramatic difference as this will eliminate glare from those pesky street/house lights to a large extent.

Unfortunately, this year's Ursid peak coincides with the Full Moon. The good news: even the Moon won't be able to drown-out the brightest meteors with all its light.

Sunday, December 20, 2015

Tonight's Sky for December 20: Moon at Perigee

Tonight, the Moon is about as big as it will ever get thanks to the fact that the Moon is at perigee, a point in its orbit that is closest to Earth.


What many people may not realize is the fact that the Moon (and all other celestial bodies) do not orbit their parent bodies in circles, but ellipses, which are slightly elongated circles. Result: any given day of an orbital period, any orbiting body will be at a slightly different distance from its parent body. As for the Moon, this variance in orbit amounts to about 20,000 miles.

As for tonight, the Moon will be about as close to Earth as it is going to get. When it comes to practical implications, the difference will be hard to notice with the naked eye to all but an experienced observer but, in a telescope, the difference will be obvious

Friday, December 18, 2015

Tonight's Sky for December 18: First Quarter Moon


Today, the Moon, second brightest object in the sky, has reached the First Quarter phase, which means that it is exactly 90 degrees around its orbit of Earth and is one quarter finished with its current orbit..

As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, with the Moon at a 90 degree angle relative to the Earth-Sun line, we only see half of the lit side.

After today, we will see more of the Moon each night as its lit side turns more toward from us and heads toward Full in a week. 

Wednesday, December 16, 2015

Tonight's Sky for December 17: First Powered Flight (1903)

It was on this date in 1903 that the Wright Brothers made the first powered flight in human history. While earlier flights had been made with hot air balloons, the first heavier than air flight was a milestone for the simple reason that many people thought that it could never be done in the first place. While Orville Wright only got the Flyer a few feet off the ground for 12 seconds and traveled only about 120 feet, it was the root of all flight to follow, which would culminate in Apollo 11's Moon landing in 1969.

Tonight's Sky for December 16: E.E. Barnard Born (1857)

It was on this date in 1857 that the American astronomer Edward Emerson Barnard was born in Nashville, Tennessee.

Barnard gained fame as an amateur astronomer. As a hobbyist, Barnard discovered 5 comets after Hulbert Harrington Warner offered a prize of $200 per comet discovery. With this money, Barnard built a house for himself and his wife. This feat propelling him to fame, a group of Nashville amateurs pooled enough money to get Barnard into Vanderbilt University. Barnard never graduated but received the only honorary degree Vanderbilt ever awarded.

From there, Barnard moved onto working at observatories, where he discovered Iapetus and Amalthea, the fifth Moon of Jupiter and the last to be discovered visually. Working at the Yerkes Observatory, Barnard used the great 40-inch refractor and became a pioneer astrophotographer. Additionally, he discovered Barnard's Star, the second closest to Earth.

Tuesday, December 15, 2015

Tonight's Sky for December 15: Venera 7 Lands on Venus (1970)

It was on this date in 1970 that the Russian-built Venera 7 became the first spacecraft to both land on and transmit data from another planet. The data transmitted was minimal, a temperature reading of 887 degrees Fahrenheit, but it was the first data ever transmitted back to Earth from another planet. Later investigation came to the conclusion that the craft had probably bounced on landing and came to rest on its side, thus preventing the transmission of any further data thanks to the fact t hat the antenna was pointed down to the ground. 

Tonight's Sky for December 14: Geminids Peak

Tonight will mark the peak of the Geminid Meteor shower for 2015, thus marking the climax for the 2-week event. Every December, Earth passes through the stretch of space junk shed by the mysterious 3200 Phaeton (thought to be a spent comet now resembling an asteroid because all of its ice has melted), reaching the deepest concentration of debris tonight. According to some estimates, under ideal conditions (dark country skies), one can expect to see 100 meteors per hour. The reason the meteors are called Geminids is because the meteors seem to radiate from the constellation Gemini. The best time to view the shower is in the predawn, as Gemini is at its highest then.

Don't want to stay up that late? Don't worry, Gemini is clears the horizon around the time the sky gets truly dark, making this an all-night event. However, unless one lives out in the country, the early night hours will probably involve Gemini being low in a light dome. To improve odds of seeing meteors, travel out of the city and to the country if you can. In the suburbs, just going from the front to back yard can make a dramatic difference as this will eliminate glare from those pesky street/house lights to a large extent.

Fortunately, this year's shower coincides with the waxing crescent Moon, which means that nature's night light will be a non-issue. 

Sunday, December 13, 2015

Tonight's Sky for December 13: Thin Crescent

Didn't see last night's 12-hour Moon? Well, tonight's 36-hour Moon is no challenge to spot but still very appealing for people who like to observe thin crescents.

Saturday, December 12, 2015

Tonight's Sky for December 12: The Youngest of Moons

How thin of a Moon have you seen? How about one that's just barely over 12 hours old and only 0.5% illuminated? Well, if you have never seen a Moon this thin, this is your chance to do so as such a Moon will be making an appearance in this evening's sky just after sunset. 

To see the Moon, you'll need a good Western horizon. How good? One with less than 3 degrees of obstruction. To simulate this, hold your little finger vertically at arm's length to simulate 1 degrees. Hint: if you can't think of a good location off-hand, scout out one during the day. Location found, head there at sunset and start looking, preferably with optical aid, and start scanning the sky. The Moon may not be visible at first, often seeming to suddenly pop into visibility as if it were flipped on like a light.

Believe me, when this happens, it's an exhilarating experience but note: seeing a 12-hour Moon is a very, very (can't emphasize the 'very' enough) tough proposition as it is near the world record for the youngest Moon sighting. Hint: if you have a go-to scope, this would be a great time to utilize it! 

Friday, December 11, 2015

Tonight's Sky for December 11: New Moon


Today, the Moon, second brightest object in the sky, has reached the New Moon phase, which means that it is directly between the Sun and Earth, and thus invisible for us Earthlings as of now.

As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, with the Moon directly between the Earth and Sun, we can't see any of its lit side. 

Wednesday, December 9, 2015

Tonight's Sky for December 8: Astraea Discovered (1845)

It was on this date in 1845 that H.L. Hencke discovered Astraea, the 5th known asteroid. The first asteroid, Ceres (now classified as a dwarf planet), was discovered in 1801. In the intervening years, 3 more discoveries followed: Pallas, Juno, and Vesta. Interestingly, at the time of its discovery, Astraea was classified as a planet, along with the other 4 objects now known to reside in the asteroid belt. However, with the advances in lens making that made the construction of far larger telescopes possible, the discovery of objects in the asteroid belt accelerated to the point where it became too cumbersome to classify these objects as planets. Result: by the end of the 1850s, these objects were known as asteroids (from the Greek for 'star-like') and, as more were discovered, the term 'asteroid belt' eventually came into use.

Monday, December 7, 2015

Tonight's Sky for December 7: Moon Meets Venus


Want to see the planet Venus but have no idea where to look? Well, no problem because, at least for this morning, the Moon will be parked right next to Venus, second planet from the Sun and third brightest object in the sky (after the Sun and Moon).

Sunday, December 6, 2015

Tonight's Sky for December 6: Mars Rises 5 Hours Before the Sun With Moon

Want to see the planet Mars but have no idea where to look? Well, no problem because, at least for this morning, the Moon will be parked right next to Mars, fourth planet from the Sun. Try and see if you can notice its reddish tinge when compared to close-by Venus and Jupiter.


Additionally, Mars is now rising 5 hours before the Sun.

Saturday, December 5, 2015

Tonight's Sky for December 5: The Earliest Sunsets, Moon at Apogee

While the shortest day of the year, the Winter Solstice, is about two weeks away, the earliest sunsets of the year will occur this week for us here on Earth, regardless of where you live, despite the fact that sunset times vary depending on latitude.
Right now, the Sun is setting at its earliest time and will continue to set at the same time for the next few days before gradually creeping later into the evening.
So, with the Sun down so early (and resulting in the longest nights of the year), why not head out and view the stars? After all, the December sky has a lot to offer. After all, at what point of the year can you see a year's worth of stars in a given night? Don't believe me? Head out just after dark tonight and look up for the Summer Triangle. Then, just before sunrise, go out again and look for a bright blue star in the Northeast just above the horizon. That's Vega, the same Summer Triangle Star you saw the previous night.

Additionally, the Moon is about as small as it will ever get thanks to the fact that the Moon is at apogee, a point in its orbit that is farthest from Earth.


What many people may not realize is the fact that the Moon (and all other celestial bodies) do not orbit their parent bodies in circles, but ellipses, which are slightly elongated circles. Result: any given day of an orbital period, any orbiting body will be at a slightly different distance from its parent body. As for the Moon, this variance in orbit amounts to about 20,000 miles.

As for tonight, the Moon will be about as far from Earth as it is going to get. When it comes to practical implications, the difference will be hard to notice with the naked eye to all but an experienced observer but, in a telescope, the difference will be obvious

Friday, December 4, 2015

Tonight's Sky for December 4: Moon Meets Jupiter

Want to see the planet Jupiter but have no idea where to look? Well, no problem because, at least for this morning, the Moon will be parked right next to Jupiter, fifth planet from the Sun and largest planet in the solar system.  

Thursday, December 3, 2015

Tonight's Sky for December 3: Third Quarter Moon


Today, the Moon, second brightest object in the sky, has reached the Third Quarter phase, which means that it is exactly 270 degrees around its orbit of Earth.

As for lunar mechanics, the Moon is always half lit. The reason we don't always see it as such is thanks to orientation in relation to us. Right now, with the Moon at a 90 degree angle relative to the Earth and Sun, we see the Moon as half lit and half dark, leading to the popular, erroneous phrase 'half Moon.'

After today, we will see less and less of the Moon as its lit side turns more away from us and heads toward new phase.

Wednesday, December 2, 2015

Tonight's Sky for December 2: Moon Meets Regulus

New to astronomy? Want to see Regulus, the alpha (brightest star) in Leo but don't know where to look? Well, it's your lucky night as the Moon will be right next to Regulus this morning. 

The moon is, of course, impossible to miss. As for Spica, it's that bright star right next to Luna. To see the show, go out early in the night just after the sky gets dark.

Tuesday, December 1, 2015

The December Sky

With new month of December upon us, people in the Northern Hemisphere will be treated to the longest nights of the year as the Winter Solstice arrives on the 22nd of this month. However, when it comes to changes in days' lengths, December is pretty much a story of steady 15 hour nights, give or take a few minutes at most. So, with all of this night, what's there to see?

Cool Constellations
By nightfall in December the fall constellations are all very well-placed for early (emphasis, early!) evening viewing. First up, we will have one last chance to see the summer constellations, provided you have a good West horizon. Hurry, though, they'll quickly disappear (at least in the West) for good by month's end. Moving onto more mainstream celestial landmarks for this time of year, the Great Square of Pegasus is high overhead and the Big Dipper is scraping the Northern horizon. Starting at the Great Square, look at the double string of stars coming of third base as they constitute Andromeda. High in the Northeast is ‘W’-shaped Cassiopeia, house-like Cepheus, and a twisted ‘V’ of stars, the mythological hero Perseus. Below Perseus is the bright Capella, alpha Auriga, and below his feet, the cloudy patch that is the Pleiades. In the early evening, the South, save bright Fomalhaut, is a dark void populated by the dim constellations of Capricorn, Aquarius, Pisces, and Cetus. If you stay up a little later as in a couple of hours after dark (which is no longer a chore/something you later regret doing at this time of year), you'll see all the winter favorite like unmistakable Orion in the South, which also serves as a winter signpost to the stars. From Orion, follow a line from his belt down to blazing blue Sirius, alpha Canis Major. Following that line up will bring one to Aldebaran, alpha Taurus the bull. Imagining a line starting at bright blue Rigel (Orion's left foot) through red Betelgeuse (Orion's right shoulder) will bring you to Castor and Pollux, alpha and beta Gemini. Other winter favorites to look for include Canis Minor, Cancer, and even Leo if you wait into the night a little longer. Early birds? Well, getting up just before the Sun will bring a spring preview in the form of Virgo, Bootes, Corona, Hercules, Corvus, and even Vega just ahead of the rising Sun.

Planetary Perceptions
On the planet front, if you want to see any of our solar system neighbors, you had better be an early bird because 4 of the 5 naked eye planets make their appearances in the predawn morning sky. For starters, Jupiter and Mars both continue their climbs in the predawn Eastern sky while Venus continues dropping, which is what it began to do in October and then, noticeably in November. Also of note, the Moon will be making several near passes of these bodies in the early part of the month. As for Saturn, which disappeared into the dusk glow back in mid November, it re-emerges as a morning planet mid month and, by month's end, should be relatively easy to spot low in the predawn, Eastern sky. As for Mercury, it will become the sole evening planet when it pops out of the Sun's glare in the evening sky mid month as it heads towards greatest elongation (best visibility) around the start of the new year.


Tonight's Sky for December 1: Benjamin Wilson Born (1811)
It was on this date that Benjamin Wilson, namesake of Mt. Wilson, was born. Originally from Tennessee, Wilson traveled to California hoping to obtain passage to China but was unable to do so. Instead of traveling back home, Wilson settled in Southern California where he became a prominent politician and businessman. Wilson died in 1878 at age 66 and Mt. Wilson, Informally known as Wilson's Mountain because he owned the land on which it sat, thte name would eventually become official.