Skywatch Line for Wednesday, March 22nd, and Thursday, March 23rd, 2017

This is the Dudley Observatory Skywatch Line for Wednesday, March 22nd, and Thursday, March 23rd, written by Louis Suarato.

The 31% illuminated, waning crescent Moon sets at 1:30 p.m. Wednesday in the constellation Sagittarius. The Moon rises again as a 25% illuminated crescent at 4:15 a.m. Thursday in Capricornus. Venus may be too close to the Sun to view after sunset, but you still may be able to find our closest planetary neighbor in daylight using binoculars. Be careful not to look too close to the Sun. Look for Mercury around 7:30 p.m. about 10 degrees above the western horizon. Mars shines about 20 degrees above Mercury between the constellations Cetus and Aries. Jupiter rises at 8:33 p.m. in Virgo. Jupiter’s moon Europa begins it shadow transit at 1:23 a.m. Thursday, and at 2:11 a.m., Europa transits the planet. Europa’s shadow transit ends at 3:52 a.m., and 40 minutes later, Europa exits the face of our solar system’s largest planet. Saturn rises at 2:09 a.m. in Sagittarius.

There’s a 7th magnitude comet approaching the Big Dipper. The comet, 41P/Tuttle-Giocobini-Kresak, is traveling toward the pointer stars, or outermost stars, of the Big Dipper’s bowl. Wednesday and Thursday nights, look 5 to 7 degrees above the star Merak, which is the lower, outermost star of the Big Dipper’s bowl. Through binoculars, Comet 41P/Tuttle-Giacobini-Kresak will look like a green, fuzzy ball. This comet is approaching its closest pass to Earth, and at the end of the month will be 13.2 million miles away, the closest it’s been in a century. The comet may also reach 6th magnitude by the end of the month. Comet 41P/Tuttle-Giacobini-Kresak was first discovered by Horace Parnell Tuttle on May 3, 1858. It was rediscovered by Michael Giacobini in 1907, and by LuborKresak in 1951. Comet 41P/Tuttle-Giacobini-Kresak is a member of the Jupiter family of comets and its orbital period is estimated to be between 5.8 and 7.5 years.

Skywatch Line for Monday and Tuesday, March 20th and 21st, 2017

This is the Skywatch Line for Monday and Tuesday, March 20th and 21st.

The Sun sets at 7:08PM; night falls at 8:43. Dawn breaks at 5:21 AM and ends with the Sun rising at 6:56.

The Vernal Equinox took place at 6:29 Monday morning, signaling the beginning of astronomical spring. Astronomers define Spring as that point when the ecliptic (the Sun’s path across the sky) and the celestial equator (the projection of Earth’s equator onto the sky) cross with the Sun climbing higher on the ecliptic.

The southwest evening sky contains three bright planets and one dim one, all in Pisces. Pisces houses Venus, Mercury and Uranus. Venus is brightest and lowest, blazing at minus fourth magnitude but appearing only 2 percent illuminated. Shortly, it will disappear behind the Sun. Venus sets at 8 PM. Weather permitting, observers can enjoy a rare event. Tuesday, Venus sets about 30 minutes after the Sun, and rises 33 minutes before the Sun on Wednesday. Clear western and eastern horizons afford views of the planet before those times.

Ten degrees to Venus’ upper left is Mercury, beginning its best appearance of the year. Mercury blazes at minus first magnitude, appears about 84 percent illuminated and six degrees high. Mercury sets at 8:15 PM. Nine degrees to Mercury’s upper left is much dimmer Uranus, shining at sixth magnitude and about 15 degrees high; Uranus sets at 9 PM. Fifteen degrees to Uranus’ upper left is first magnitude Mars, now in Aries. It appears as a tiny red dot but 29 degrees high. Mars sets at 10:20 PM.

Nightfall reveals dim seventh magnitude asteroid 4Vesta. It lies about 1 degree below the star Upsilon Geminorum and is best observed at 8:30 PM.

Jupiter rises at 8:39 PM in Virgo. It glows at minus second magnitude, outshining first magnitude star Spica below. Jupiter is best observed at 2:20 AM. Telescopic observers can witness the Great Red Spot, a giant storm, at 4:03 AM on Tuesday and at 11:54 PM on Wednesday. Jupiter remains up the rest of the night.

Saturn rises at 2:12 AM in Sagittarius. The Ringed Planet appears a creamy white 0.5 magnitude twenty-two degrees high in the eastern sky.

The Last Quarter Moon rises, also in Sagittarius, at 2:46 AM. Its minus ninth magnitude will washout dim deep sky objects. The Moon appears 30 minutes large and about 43 percent illuminated. Wednesday, a slightly fainter and slimmer Moon rises about 3:33 AM.

A chain of stars wraps itself around Polaris, the Pole Star; this group is the constellation Draco, the Dragon. Draco is ancient, going back to the Mesopotamians. Most legends picture dragons as we do, with horns, wings and multiple heads. Several Greek legends have the dragon guarding the Golden Apples or the Golden Fleece. In our night sky, Draco seems to continue his role as protector of the Pole Star. However, when the Pyramids were built, Thuban, one of Draco’s stars was, itself, the Pole Star. Several of the Pyramids were oriented to it.

Skywatch Line for Friday, March 17, through Sunday, March 19, 2017

This is Dudley Observatory’s Skywatch Line for Friday, March 17, through Sunday, March 19, written by Sam Salem.

On Friday, Sun rises at 7:04am and sets at 7:05pm; the 77% illuminated Waning Gibbous Moon rises at 11:12pm on preceding day, reaching transit altitude of 33 degrees south at 4:34am and sets at 9:52am. The Spring Equinox comes on Monday at 6:29am EDT.

Venus is the first star-like object to shine into the evening twilight. You might be able to see Venus as soon as a few minutes after sunset. Venus will fall sunward to pass in between the Earth and Sun on March 25. Day by day, Mercury will climb upward from the setting Sun. By the month’s end, Venus will have left the evening sky, while Mercury will be at its best evening apparition of the year. At early-to-mid evening, look eastward to see Jupiter, the sky’s second brightest planet in the night sky after Venus. On Saturday, Jupiter’s moon Io, barely off Jupiter’s western limb, disappears into eclipse by Jupiter’s shadow around 10:24pm. A small telescope will show it slowly fade away. In a dark sky, try to locate constellation Corvus near Jupiter and Spica, the brightest star in the constellation Virgo, the Maiden. Use the waning Moon to guide you to the star Antares and the planet Saturn over the next several mornings.

The dim constellation Cancer is on the traditional divide between the winter and spring sky. It lies between Gemini to its west and Leo to its east. Constellation Cancer holds the Beehive Star Cluster, M44, in its middle. The Beehive is one of the nearest open clusters to the Solar System. Under dark skies the Beehive Cluster looks like a nebulous object to the naked eye. It was among the first objects that Galileo studied with his telescope. Look for it a little less than halfway from Pollux, in Gemini to Regulus, in Leo.

Orion has moved and turned considerably in the last few weeks. Depending on latitude, the farther south, the longer Orion can be seen in the night sky. For our area and for most of the United States, Orion will be gone by the time of the summer solstice, in June.

On March 17 1899, William Henry Pickering observed Phoebe, the ninth moon of Saturn, as a very faint object on a photographic plate. taken in August a year before. The image was captured in August 1898 on a 14 x 17 inches plate exposed for two hours in the telescope at the Harvard station near Arequipa, Peru.

Skywatch Line for Wednesday, March 15th, and Thursday, March 16th, 2017

This is the Dudley Observatory Skywatch Line for Wednesday, March 15th, and Thursday, March 16th, written by Louis Suarato.
Venus is in retrograde motion, traveling toward the Sun, and is about 17 degrees above the horizon at sunset. Wednesday night, Venus shines as a 4.2% illuminated disk. Use binoculars or a telescope to see crescent Venus before it get too close to the setting sun. Venus reaches inferior conjunction on March 25th, and will emerge as a morning star by the end of the month. Mercury passes 9.5 degrees from Venus, but is still too close to the Sun to view. Look for Mercury in the evening sky toward month’s end. The distance between Venus and Mars increases, as Mars moves into the constellation Aries. Jupiter rises just after 9 p.m. in Virgo, followed by the 88% illuminated, waning gibbous Moon an hour and half later. The shadow of Jupiter’s moon Europa begins transiting the planet at 10:47 p.m., followed by Europa at 11:55 p.m.. Europa’s shadow transit ends at 1:16 a.m. Thursday, and Europa’s transit ends one hour later. Saturn rises in the “steam” of the Teapot asterism at 2:39 a.m. in Sagittarius. Look to the upper left of Saturn for the open star cluster M23. To Saturn’s lower left is open star cluster NGC 6469. To the lower left of NGC 6469 is the Trifid nebula.
For the next two weeks, the Zodiacal Light is visible rising up from the western horizon after sunset. The Zodiacal Light is a conical white glow that extends from the point of sunset and up toward the ecliptic. This light is the reflection of interplanetary dust caused by the mostly dormant Jupiter family of comets. As with most astronomical observations, the darker the skies, the better chance you have to observe this phenomenon.
March 16th is the birth date of astronomer Caroline Herschel. Born in 1750, Caroline, although sometimes lost in shadow of her brother William’s fame, discovered eight comets and three nebulae.
The Albany Area Amateur Astronomers will be hosting their monthly meeting this Thursday night at 7:30 at miSci in Schenectady. This month’s speaker is long time club member and Sky & Telescope columnist Sue French. The topic is “The Inquiring Observer”. Non-members are always welcome.

Skywatch Line for Friday, March 10, through Sunday, March 12, 2017

This is Dudley Observatory’s Skywatch Line for Friday, March 10, through Sunday, March 12, written by Sam Salem.

On Friday, Sun rises at 6:16am and sets at 5:56pm; the 96% illuminated Waxing Gibbous Moon reaches transit altitude of 57 degrees south at 11:00pm and sets before sunrise at 5:12am. The Daylight Saving Time begins at 2:00am on Sunday. Saturday night’s Moon will appear full to the eye all night long. However, the Moon turns exactly full on Sunday at 10:54am.This is the third full Moon this year, which is called the Worm Moon, Crow Moon, or Sap Moon. This full Moon is the closest to the March 20 Spring Equinox. On Sunday night, look eastward as darkness falls to see the Moon. Watch for Jupiter to follow the Moon into the night sky by early evening. The Moon and Jupiter will climb upward during the evening hours, reaching their high point for the night somewhat after midnight.

As darkness falls on Friday, Regulus, the brightest star in the constellation Leo, the Lion, appears near the Moon. The Moon will be 2.5 degrees lower left of Regulus. Spotting Regulus in the glare of the Waxing Gibbous Moon might not be easy. Regulus is one of the four Royal Stars of ancient Persia. These Royal Stars, Regulus, Antares, Fomalhaut, and Aldebaran, mark the four quadrants of the sky. Thousands of years ago, the Royal Stars defined the approximate positions of Equinoxes and Solstices in the sky. Regulus, often portrayed as the most significant Royal Star, ruled as the summer Solstice star, Antares as the autumn Equinox star, Fomalhaut as the winter Solstice star, and Aldebaran as the spring Equinox star.

Uranus, at 5.9 magnitude, resides in constellation Pisces in the west at nightfall between Mars and Venus. Direct observations of Uranus rings from Earth had not been possible because the rings are lost in the planet’s glare as seen through terrestrial optical telescopes. Friday marks the 40th anniversary of the discovery of Uranus’ rings from Earth. On March 10, 1977, a star occultation with Uranus unexpectedly revealed its rings. The ringed planet blocked the starlight, but the star disappeared from view five times. This data suggested that Uranus was surrounded by at least five rings. Four more rings were suggested by subsequent occultation measurements from the Earth, and two additional ones were found by space probe Voyager 2. Two outer rings were found in 2003–2005 in Hubble Space Telescope photos. William Herschel, who uncovered Uranus in 1781, reported observing a ring system around Uranus more than 200 years ago. It is not known whether something had caused the rings to brighten at that time, or was Herschel’s observation in error.

Saturday marks the birthdate of the French Astronomer Urbain-Jean-Joseph Le Verrier. Born in 1811, Le Verrier predicted by mathematical means the existence of the planet Neptune. He calculated the position of Neptune from irregularities in Uranus’s orbit. As his contemporaries described it, he discovered a planet with the tip of his pen, without any instrument other than the strength of his calculations alone. In 1856, the German astronomer Johan G. Galle discovered

Neptune within one degree of the position that had been computed by Le Verrier, the same night he received the coordinates. The discovery of Neptune is one of the most remarkable moments of 19th century science giving the most striking confirmation of Newton’s theory of gravitation.

Skywatch Line for Wednesday, March 8th, and Thursday, March 9th, 2017

This is the Dudley Observatory Skywatch Line for Wednesday, March 8th, and Thursday, March 9th, written by Louis Suarato.

The 84% illuminated, waxing gibbous Moon rises at 1:54 p.m. Wednesday in the constellation Cancer. At nightfall, look about 8 degrees to the Moon’s upper left to see the Beehive Cluster, or M44. To the Moon’s right is the asterism known as the Winter Hexigon, comprised of the stars Rigel in Orion, Aldebaran in Taurus, Capella in Auriga, Pollux in Gemini, Procyon in CanisMinor, and Sirius in Canis Major. Over the western horizon, Venus shines brightest as a 10% illuminated crescent. Venus will set a few minutes after 8 p.m. Wednesday. Mars can be found higher along the ecliptic in the constellation Aries, with Uranus between our neighboring planets. Jupiter rises at 8:30 p.m. in Virgo. As Jupiter is rising, its moon Europa will be transiting the planet. Europa’s shadow transit ends at 9:41 p.m., and at 22:58 p.m., Europa’s transit ends. Saturn rises after 2 a.m. Thursday in Sagittarius. Saturn will remain the only planet visible in the dawn sky until it is joined by Venus later this month.

March 8th is the birth date of telescope making pioneer AlvanClark. Born in 1804, Clark, and later, his sons, became famous for making refracting telescopes for many observatories, including the 18.5 inch refractor at the Dearborn Observatory in the University of Chicago, then, the largest refracting telescope in the world. While testing one of his telescopes, on January 31, 1862, Clark discovered the companion star to Sirius. The Clark Comet Seeker telescope can be seen at the Dudley Observatory. The Comet Seeker has a four inch object glass and a focal length of three feet. It was used by the astronomer Christian Henry Peters to make the first discovery ever by a Dudley Observatory astronomer, a comet found by Peters in 1857 and named for one of the Observatory trustees, Thomas W. Olcott. Later Dudley Observatory assistant Charles Wells used it in 1882 to discover the first comet of that year.

Skywatch Line for Monday and Tuesday, March 6th and 7th, 2017

This is the Skywatch Line for Monday and Tuesday, March 6th and 7th.

The Sun sets at 5:51 PM; night falls at 7:25. Dawn breaks at 4:47 AM and ends with the Sun rising at 6:21.

The Moon and two bright planets grace the darkening sky. The nine-day-old Moon rises about Noon on Monday in Gemini and blazes at minus 10th magnitude, appearing about two-thirds lit. Tuesday finds it slightly brighter and fatter. The Moon sets at 2:53 AM on Tuesday, and at 3:46 AM on Wednesday.

Three planets inhabit the moderately low western constellation of Pisces. Venus is next brightest at minus 4th magnitude, appearing large in our telescopes, but a slender 11 percent illuminated. This month, it dims slightly and its crescent thins to a hairline, but it appears slightly larger in our instruments. It sets at 8:20 PM. Mars, 17 degrees to Venus’ left, is next brightest at first magnitude and is easily identified by its red color. Mars sets about 9:22 PM.
Nightfall reveals Uranus, about 5 degrees to Mars’ lower right. This blue-green planet is much dimmer at sixth magnitude and appears tiny in telescopes; the observer should consult sky charts from astronomical media for a detailed location. Uranus sets at 8:53 PM.

Minor planet 4Vesta is also visible at twilight’s end. It shines at 7th magnitude, appears a tiny 0.4 arc-seconds, and lies about two degrees below the star Upsilon in Gemini. Again, detailed star charts help find it. It sets at 4 AM.

By 10 PM, Comet 45P appears above Leo’s back. Another challenge object, it is a dim 14th magnitude and a tiny size.
It is best observed at about 11:49 PM, again assisted by sky charts.

Jupiter rises in Virgo at 8:42 PM. It blazes at minus 2nd magnitude, above the 1st magnitude star Spica. This month Jupiter begins a retrograde (westward) trek; it also brightens and enlarges slightly. At 1:02 AM on Tuesday, the telescopic observer can witness the moon Europa disappear behind Jupiter and reappear at 4:52 AM. Jupiter is best observed at 2:17 AM.

Finally, Saturn rises in Sagittarius at 2:06 AM. It shines at zero magnitude and is moderately large in our telescopes. By Dawn, it is high enough to enjoy views of its beautiful rings.
Since Jupiter and Saturn are visible simultaneously, comparisons are in order. Both are gas giants – planets composed mostly of gas. Jupiter is larger; Saturn is about a third of Jupiter’s mass. In telescopes, Jupiter’s colored bands signify active weather systems; one storm, the Great Red Spot, has been continuously observed for centuries. Saturn’s weather appears more subdued, with occasional faint features. Saturn’s ring system is easily visible from Earth. Jupiter’s rings are observable only from space-borne telescopes. Both planets’ 120 moons account for most of the Solar System’s total. Four of Jupiter’s moons appear in binoculars, while Saturn’s satellites can only be spotted through a telescope. Jupiter’s moon Io is the most volcanically active moon in the Solar System, while Europa, Ganymede and Callisto may conceal oceans beneath their icy surfaces. Saturn’s moons Enceladus and Titan are geologically active, which spurt ice fountains. Titan is the only moon to have an atmosphere; however, its atmosphere contains cold methane, rather than oxygen. Titan also has vast lakes of liquid methane on its surface.

Skywatch Line for Friday, March 3, through Sunday, March 5, 2017

This is Dudley Observatory’s Skywatch Line for Friday, March 3, through Sunday, March 5, written by Sam Salem.

On Friday, Sun rises at 6:28am and sets at 5:48pm; the 30% illuminated Waxing Crescent Moon rises at 9:33am, reaching transit altitude of 60 degrees south at 4:34pm, and sets at 11:44pm. The Moon reaches first-quarter phase on Sunday at 6:32am. On Saturday, the dark limb of the almost first-quarter Moon occults Aldebaran for viewers in most of the United States, Mexico, and Central America. That evening, the Moon visits the Hyades cluster in Taurus Constellation and moves south of Aldebaran, the constellation’s brightest star. The Moon will be 0.2 degrees east of Aldebaran shortly after 11pm. Aldebaran disappears around 11:10pm and reappears around 11:30pm. On its way through the Hyades, the dark limb of the Moon will cover several moderately bright stars. As the Moon slowly shifts eastward, the hills and valleys along the northern edge of the lunar disk will cause Aldebaran to blink off and on multiple times. Few observers across southern Canada and the northern United States will get to witness this rare “grazing” occultation. The International Occultation Timing Association has set up a special web page for the Aldebaran graze, with Google Maps of the northern graze line from Connecticut across the Great Lakes to Vancouver. http://occultations.org/aldebaran/2017march/

Venus at magnitude -4.8 shines shortly after sunset. Almost 13 degrees above and to the left of Venus is Mars, glowing at magnitude 1.3. Jupiter at magnitude -2.3 rises in the east above Spica in Virgo. It climbs to the meridian around 3:00am. Saturn at magnitude 0.5 is located in the southern Ophiuchus, between constellations Scorpius and Sagittarius, and rises shortly after 2:30am.

On Sunday night, the Moon resides inside the Winter Circle, a large star configuration made of seven brilliant stars. In the Northern Hemisphere, we see the Winter Circle fill up much of the southern sky at nightfall. The Winter Circle, or the Winter Hexagon, is a pattern of stars that’s easy to recognize. At nightfall, look high up for the bright star Capella. This star marks the top of the Winter Circle. As darkness falls, look for the constellation Orion, the Hunter. Draw a line downward through Orion’s Belt to find Sirius, the brightest star in the night sky. Sirius marks the bottom, or the southern tip, of the Winter Circle.

Spot Capella, the brightest star in constellation Auriga, with unaided eye before sunset this weekend. Capella reaches transit altitude of 87 degrees north, almost 40 minutes after sunset, at 6:26pm on Friday.

Skywatch Line for Wednesday, March 1st, and Thursday, March 2nd, 2017

This is the Dudley Observatory Skywatch Line for Wednesday, March 1st, and Thursday, March 2nd, written by Louis Suarato.

The old adage states that “March comes in like a lion and goes out like a lamb.” Most use that idiom to refer to the weather, but it’s also true astronomically. Wednesday evening, look above the eastern horizon to see the constellation Leo “The Lion”. Leo is the 12th largest constellation, and is most prominent from February through May. Leo’s brightest star is Regulus, which can be found to the lower right of the lion’s neck and head, an asterism known as the sickle. Regulus, or Alpha Leonis, located79 light-years from the Sun, is the closest of the brightest stars in our sky. Regulus is a multiple star system of four stars, comprised of two pairs. One pair consists of Regulus A, a blue-white star, and its companion star. Regulus A is about 3.5 times the mass of our Sun, with a rotation period of 15.9 hours. This rapid rotation causes the star to have an oblate shape. The Regulus system forms the 21st brightest star in our sky at magnitude +1.35.

The 14% illuminated, waxing crescent Moon can be seen in the constellation Pisces, 5 degrees to the left of Mars. Binoculars will help you find Uranus, 2 degrees below Mars. Venus shines brightly to the lower right of the two planets and crescent Moon. Thursday, the Moon passes within a degree of the dwarf planet Ceres. You will need binoculars or a small telescope to see 9.04 magnitude Ceres to the right of the crescent Moon. Jupiter risesat 9:06 p.m. in Virgo. As Jupiter climbs the sky, a telescopic view will show its moon Europa, and its shadow transiting the planet. Europa’s shadow transit ends at 7:07 p.m., and Europa’s transit ends at 8:39 p.m. Wednesday. Thursday night, Jupiter’s moon Ganymede, and its shadow transit the planet as it rises. Ganymede’s shadow transit ends at 8:10 p.m., and Ganymede’s transit ends at 11:02 p.m.. Saturn rises at 2:28 a.m. in Ophiuchus.

Skywatch Line for Monday and Tuesday, February 27th and 28th, 2017

This is the Skywatch Line for Monday and Tuesday, February 27th and 28th.

The Sun sets at 5:42 PM; night falls at 7:16. Dawn breaks at
4:58 AM and ends with sunrise at 6:32.

The darkening sky reveals the Moon and three planets, all in Pisces. A very young Moon (one-day-old), appears bright, very thin and very low, only eight degrees above the western horizon. It migrates from Aquarius to Cetus on Tuesday, appears slightly fuller but much brighter, at minus 4th magnitude nearer to Venus. The Moon sets at 7:09 PM on Monday, 8:13 PM on Tuesday.

Venus is the brightest object in the sky, at minus 4.6 magnitude, and appears about 18 percent lit. It sets at 8:44 PM. First magnitude Mars glows red about 12 degrees to Venus’ left. In our telescopes, it is a tiny 4.6 arc-seconds in size, but about 95 percent illuminated. Mars sets at 9:23 PM.

Nightfall reveals sixth magnitude Uranus less than a degree away from Mars. It is also a tiny 3.4 arc-seconds in size, but its blue-green color aids in identification. Uranus sets at 9:18 PM.

Comet 2Encke is an early evening challenge. It inhabits Pisces with its planetary cousins, but is only seven degrees above the western horizon, shines at 5th magnitude and may be difficult to find with the Moon nearby. It is a frequent visitor to our skies, returning every 3.3 years. Encke sets at 7:57 PM.

Asteroid 4Vesta is a bit easier to find, within 2 degrees of the star Upsilon Geminorum. It also is tiny in in our telescopes and dimmer at seventh magnitude. It is best observed at 8:53 PM and sets at 4:43 AM. Comet 45P is dimmer yet, at 12th magnitude and is located between the Big Bear’s hind leg and Leo’s hip. All three require detailed sky charts found in various astronomical media.

Jupiter rises at 9:12 PM just above the bright star Spica in Virgo. It shines at minus 2.3 magnitude and is a large 42 arc-seconds in size. It is best observed at 2:47 AM and remains up the rest of the night.

Saturn, second in size to Jupiter, rises in Sagittarius at 2:32 AM, shines at 0.5 magnitude and is 16 arc-seconds in size. It is best observed before Dawn, when its ring system is prominent.

Romulus, the legendary founder of Rome, established the Roman calendar. The first month was Martius, named for Mars – the god of war. Following months were: Aprilis, Maius, Junius, Quintilis, Sextilis, September, October, November and December. His successor, King Numa, added Januarius and Februarius; this completed a calendar of 12 months and 354 days. Julius Caesar made January the first month (after the god of beginnings). The Roman Senate named a month for him – July, and stole a day from February to make a 31-day month. Augustus, his successor, named a month for himself and borrowed another day from February to give August also a 31-day month, leaving February with 28.