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Astronomy Club of Asheville February 2017 Sky Events The Planets this Month – page 2 The Gibbous Moon Joins the Hyades – page 5 Conjunction of Jupiter, the Moon and Spica – page 6 Planet Highlights – page 7 Moon Phases in February – page 10 Deep Penumbral Lunar Eclipse – page 11 www.AstroAsheville.org Astronomy Club of Asheville February 2017 Sky Events – the Planets A dazzlingly brilliant Venus and a much underwhelmed Mars will closely pair up all month in the south-southwest skies. Find them both at dusk in the constellation Pisces. Glowing at magnitude -4.8, Venus should be easy to locate. Look to the “Evening Star’s” upper left to spot Mars’ much fainter orange disk. Venus reaches its greatest illuminated extent (maximum illuminated area in square arcseconds) on February 17th and also its greatest brilliance of 2017. By late in the month, Venus’ diameter will be almost ten times larger than Mars and will shine about 250 times brighter! Faint Uranus, dimly glowing at 6th magnitude, is still visible in the southwest as evening twilight ends. This month it accompanies Venus and Mars in the constellation Pisces. Astronomy Club of Asheville February 2017 Sky Events – the Planets On February 26th, Mars glides just 0.6° north-northwest of Uranus. Use telescopic aid at low power or binoculars to catch both planetary disks in the same field-of-view. Neptune is heading toward an early March conjunction (on the other side of the Sun as seen from Earth) and is therefore lost in the evening twilight and the Sun’s glare all month. Jupiter, at magnitude -2.2, can be found in the constellation Virgo, rising in the east-southeast by midnight as February begins and two hours earlier, 10 p.m., by month’s end. On February 17th Jupiter reaches aphelion – its farthest point from the Sun during its orbit – for the first time in 12 years. On this day, the gas giant will be 5.46 AU, or approximately 508 million miles, from the Sun! Astronomy Club of Asheville February 2017 Sky Events – the Planets Saturn emerges from the east-southeast horizon about 2 hours before sunrise on February 1st. As it transitions through the month from the constellation Ophiuchus into Sagittarius, it will join one of the richest and most beautiful regions of the Milky Way. The ringed planet, however, is thousands of light years closer to the Earth than many of the deep-sky objects seen behind it! Mercury will be found the first three weeks of February, very low in south-southeast skies about an hour before sunrise before becoming lost in the Sun’s glare by month’s end. Binoculars will be helpful to spot this elusive planet, shining this month at magnitude -1.2, through the glow of dawn. Astronomy Club of Asheville February 2017 Sky Events – the Planets The Gibbous Moon Joins the Hyades On the evenings of Saturday and Sunday, February 4–5, the waxing gibbous moon joins the Hyades, a large open star cluster in the constellation Taurus. The red giant star Aldebaran is 65 light years behind the Moon, while the Hyades cluster is more than double this distance, at 153 light years behind the Moon! Look south, high in the sky near the meridian, about 90 minutes after sunset to catch this view. Image courtesy of Sky & Telescope Astronomy Club of Asheville February 2017 Sky Events – the Planets Dawn Conjunction of the Moon, Jupiter and Spica On the mornings of Wednesday and Thursday, February 15 and 16, a waning gibbous moon shines near Jupiter and the bright star Spica in the constellation Virgo. Our two dimensional view, as seen from the Earth, belies the fact that Moon is some 245,000 miles away on these mornings, while Jupiter is 508 million miles away and Spica is 261 light years away! Look to the southwest, about 6:15 a.m. EST, to spot this appealing conjunction. Image courtesy of Sky & Telescope Astronomy Club of Asheville February 2017 Planet Highlights Planet Avg. ConstellaDistance tion(s) from Earth Avg. Avg. Diameter Magin arc nitude seconds Mercury 1.3 AUs Sagittarius, Capricornus & Aquarius 5.3 -0.7 Venus 0.4 AUs Pisces 38.5 -4.8 Mars 1.9 AUs Pisces 4.8 +1.2 Comments Page 1 of 3 Visible low in SE dawn skies until last days of month Prominent as the “Evening Star” at dusk this month Observe early in the evening in the W-SW Astronomy Club of Asheville February 2017 Planet Highlights Avg. Distance from Earth Constellation(s) Jupiter 4.8 AUs Saturn Uranus Planet Avg. Diameter in arc seconds Avg. Magnitude Comments Virgo 40.5 -2.2 Rising in the east by 10:00 p.m. by month’s end. 10.5 AUs Ophiuchus & Sagittarius 15.9 +0.5 20.5 AUs Pisces 3.4 +5.9 Positioned low in S-SE predawn skies all month Observe it early in the evening this month Page 2 of 3 Astronomy Club of Asheville February 2017 Planet Highlights Planet Avg. ConstellaDistance tion(s) from Earth Neptune 31 AUs Aquarius Avg. Avg. Diameter Magin arc nitude seconds 2.2 +8.0 Comments Page 3 of 3 Heading towards conjunction with the Sun (other side of the Sun as seen from Earth) on Mar. 1st Astronomy Club of Asheville The Moon – February 2017 First Quarter 3rd 11:19 p.m. Full Moon** 10th 7:33 p.m. Last Quarter 18th 2:33 p.m. New Moon 26th 09:58 a.m. ** The “Snow Moon” Unless otherwise indicated, all times are EST Astronomy Club of Asheville February 2017 Highlight The February 10th Deep Penumbral Lunar Eclipse On the evening of Friday, February 10th, Asheville will experience a penumbral lunar eclipse as our full “Snow Moon” passes through the Earth’s faint outer penumbral shadow. But because the moon does not travel into the dark-red umbral section of Earth’s shadow, penumbral lunar eclipses are less than stunning and are an exercise in subtlety! The Earth’s umbral and penumbral shadows as projected into space Not shown to scale Astronomy Club of Asheville February 2017 Highlight The February 10th Deep Penumbral Lunar Eclipse While the February 10th eclipse is known as a “deep” penumbral eclipse because 98.8% of the Moon will pass through the faint penumbral shadow, with clear skies at the height of mid-eclipse expect to see only a slight darkening of the northern limb of the moon! Penumbral eclipses hardly match the splendor and drama provided by full or even partial lunar eclipses, and therefore the event could go unnoticed by most observers! ** To view, look low to the eastern horizon to locate the rising full moon. Astronomy Club of Asheville February 2017 Highlight The February 10th Deep Penumbral Lunar Eclipse Although the eclipse begins Monday evening at 5:34 p.m. EST, effects of the faint penumbral shadow on the moon won’t be visible until approximately 90 minutes before mid-eclipse. Therefore, timing for this event in Asheville is as follows (all times EST): Penumbra first visible: Mid-Eclipse: Penumbra last visible: 6:14 p.m. 7:44 p.m. 9:14 p.m. This subtle event might whet your appetite for the next total lunar eclipse to come to the eastern U.S. – in January 2019! Illustration courtesy of Sky & Telescope End