OCTOBER OKETOPA SKY GUIDE Lunar and Solar Halos Have you ever looked into the sky to see a large circle of light surrounding the THE SKY TONIGHT Sun or Moon? This otherworldly-looking phenomenon is called a halo. There’s an old meteorological saying: ring around the Octans moon means rain soon. This saying does Octans is a faint constellation in the actually have some truth to it, as solar southern sky. Not visible from the and lunar halos only appear under certain Northern Hemisphere, Octans was conditions. The sky will often look clear first created by French astronomer when these halos are present, but they result Nicolas Louis de Lacaille, who named from high, thin, cirrus clouds which contain 14 constellations in 1752, while on an thousands of tiny ice crystals that split and expedition to the Cape of Good Hope in reflect light. These cirrus clouds form in South Africa. Thirteen of the constellations advance of warm fronts, which often bring he named honoured instruments that rain as they approach and pass overhead. symbolised the Age of Enlightenment, a movement in Europe that focused Halos can also sometimes appear because on intellectual and philosophical of diamond dust. This is a ground-level ice advancement. The Octans constellation crystal cloud that forms in very cold weather. was named after an octant, a navigational Because of this, these types of halos mostly tool that allowed explorers to determine form in polar regions and aren’t as common the altitude of the Sun or a prominent star here in New Zealand. above the horizon, which they could then use to calculate the latitude of a ship. Next time you see a solar or lunar halo, pay attention to the colours you see in The constellation’s connection to them. Because the sunlight is brighter than navigation doesn’t stop there. The South moonlight, solar halos will often have more Celestial Pole (SCP), which lies directly colours visible in them while lunar halos above the southern horizon, is found in appear more monochromatic. Also, each this dim group of stars. The star Sigma halo is specific to the person looking at Octantis, also known as Polaris Australis, it, due to the orientation and position of is considered to be the Southern Pole the ice crystals in relation to your eyes. star, though it is significantly dimmer than its northern counterpart, Polaris, located in the Ursa Minor constellation and not visible in Dunedin. Because it is so faint, it is found using the Southern Cross Remember a moment in time with constellation. Throughout the night, it a personalised star chart from appears as though all the stars in the sky Otago Museum! are revolving around a motionless SCP. If you were standing on the Southern Each chart shows the position of stars, constellations, OCTOBER OKETOPA SKY GUIDE Pole in Antarctica and looked straight planets, and the sun, and the phase of the moon up, the SCP and Octans constellation for the exact time, date, and location of your would be directly above you. special event. Save 10% on your chart by enjoying a show in the Perpetual Guardian Planetarium PERPETUAL while you wait! GUARDIAN Place your order at the Museum Shop. PLANETARIUM MOON PHASES OCTOBER 2019 SUN RISE / SUNSET N 10 350 Deneb 340 20 Cygnus
330 Phase Date Andromeda30 Date Rise Set Vega Lyra First Quarter Sunday 6 October us 320 Tuesday 1 October 7.11am 7.45pm 40 Vulpecula Algol Albireo Full Moon Monday 14 October Pegasus Tuesday 15 October 6.44am 8.03pm Triangulum 310 Third Quarter Tuesday 22 October 50 Sagitta Thursday 31 October 6.17am 8.26pm Delphinus New Moon Monday 28 October Equuleus Hercules Altair 300
60 Pisces Aries Aquila VIEWING MERCURY
PLANETS Aquarius 290 70
Capricornus Scutum This month, Mercury will be at Mira Cetus 280 its greatest eastern elongation. 80 Piscis Austrinus Saturn This means it will be at the Jupiter Microscopium Ophiuchus farthest point east from the Sun Sagittarius Hine-i-tīweka Sculptor as seen from Earth. Because W Mercury is so close to the Sun, E Grus 1 October until 1.53am Jupiter it is often lost in the solar glare 15 October until 1.08am Corona Australis and difficult to see. However, 31 October until 12.18am Fornax Phoenix Telescopium from 15–24 October, it will be
Eridanus Indus 260 visible near the southwestern 100 Antares In Ophiuchus Scorpius horizon for about an hour and AchernarTucana Pavo a half after sunset. After this Libra
Horologium Ara 250 period, Mercury will appear to
Rigel110 move closer and closer to the Saturn Octans Norma Hydrus Mercury Sun, and, on 12 November, Pareārau Reticulum Lupus Caelum Triangulum Australe it will transit the Sun’s disk.
Apus 240 Ve 120 This transit will be visible from 1 October until 3.43am Lepus Mensa Dorado Rigil Kentaurus New Zealand from sunrise until 15 October until 2.50am Pictor Circinus about 7am on the 12th, but
31 October until 1.51am Columba Chamaeleon 23 0 130 Musca should only be observed with Canopus Volans In Sagittarius Sp a solar telescope or a camera
CruxAcrux
Gacrux 220 obscura, as looking directly at Time Guide 140 Sirius the sun can damage your eyes. Canis Major Carina Centaurus
ocerosThis chart is oriented for:
Early-October – 11pm 210 Venus 150 Puppis
Mid-October – 10pm
Meremere-tū-ahiahi 200 160 M
Late-October – 9pm Vela Corvus
190 170 ocyon S 1 October before 8:50pm Copyright © 2019 Heavens-Above.com 15 October before 9:30pm 31 October before 10:15pm How to use this chart: Hold the chart up to the sky and rotate it, so the direction you are looking matches the In Virgo direction printed on the bottom. For example, if you are looking south, place ’S‘ at the lower edge. Stars rise in the east and set in the west like the sun. As the Earth turns, the sky appears to rotate clockwise around the south celestial pole. The sky makes a small shift to the west every night, as the Earth rotates around the sun.