The annual Orionids meteor shower peaks this year on October 21st but unfortunately a 93% lit waning gibbous Moon will significantly interfere and reduce the number of meteors visible. Generally regarded as a strong shower, the Orionids or Orionid meteor shower is active between October 2nd and November 7th although most activity is on the peak date or a few days before or after it. In the past, rates of up to 70 per hour have been observed but normally the shower is not so active; a figure between 20 and 25 is more the norm at the moment.

Parent Comet

The Orionids parent comet is the most famous of all, Halley's Comet (1P/Halley). There are two annual meteor showers associated with Halley's Comet, the Eta Aquariids shower that occurs in May and the then the Orionids. Of the two the Orionids is by far the more prolific.

Although Halley is now in the outer solar system and will not return close to Earth until 2061, it's worth remembering that Orionid meteors result from particles leftover from the comet. Every observed Orionid is actually a small part of the famous comet streaking through and subsequently burning up in the Earth's atmosphere.

Nucleus of Halley's Comet (Halley Multicolor Camera Team, Giotto Project, ESA)

Radiant

The radiant of the Orionids is located in the north-eastern part of the constellation Orion, not far from the Gemini border. Since Orion straddles the celestial equator, the Orionids are one of the few annual showers that are well placed for observation from almost anywhere on Earth, except the polar regions.

Orionids Radiant and Star Chart

Orionids Radiant and Star Chart - pdf format

What to expect in 2013?

The major problem for 2013 is the Moon, it's almost full and will badly interfere. However, the shower is usually reliable with some bright meteors. They are fast moving and hit the atmosphere at very high speeds of 235,000 km/hour (145,000 miles/hour). At this velocity they will streak through the sky.

As with all annual meteors showers, it's best not to look directly at the radiant itself, as meteors can appear many degrees from it. A good idea this year is to try and position yourself in such a way that the Moon is out of view - for example behind a building or some trees - and then look towards the correct region of sky. This will give yourself the best chance of catching a few Orionids as they zoom by!

Orionids Data Table 2013

Meteor shower nameOrionids
Meteor shower abbreviationORI
Radiant constellationOrion
ActivityOctober 2nd -> November 7th
Peak DateOctober 21st
RA (J2000)6hr 20m
DEC (J2000)+16d
Speed (km/s)66
ZHR 20 to 25 (can vary between 20 and 70)
RatingBright
Parent body1P/Halley
NotesMost prolific meteor shower associated with Halley's Comet

Comet 1P/Halley Data Table (at epoch February 17th, 1994)

Name1P/Halley
TypeComet
ClassificationHalley-type comet (NEO)
DiscovererPrehistoric, Edmond Halley first recognised the periodicity
Discovery datePrehistoric
Aphelion (AU)35.0823
Perihelion (AU)0.58598
Semi-major axis (AU) 17.8341
Eccentricity0.96714
Orbital period (years)75.3175
Inclination (degrees) 162.263
Longitude of ascending node (degrees)58.4201
Last perihelion February 9th, 1986
Next perihelion July 28th, 2061
NotesHalley's comet, the most famous of all comets

Sky Highlights - July 2017

The Planets
This Month's Guide

Algol Minima
Algol eclipse dates and times for July

Meteor Shower
Southern Delta Aquariids (Aquarids) meteor shower peaks on July 29

Northern Hemisphere
Evening
West:- Mercury (mag. -0.5 to +0.3) (second half of month)
Southwest:- Jupiter (mag. -2.0)
South:- Saturn (mag. +0.2)
Midnight
West:- Jupiter
South:- Saturn
East:- Neptune (mag. +7.8)
Morning
Southwest:- Saturn
South:- Neptune
Southeast:- Uranus (mag. +5.8)
East:- Venus (mag. -4.1)

Southern Hemisphere
Evening
West:- Mercury (second half of month)
Northwest:- Jupiter
East:- Saturn
Midnight
West:- Jupiter
North:- Saturn
East:- Neptune
Morning
West:- Saturn
North:- Neptune
Northeast:- Venus, Uranus

Deep Sky

Small telescopes:-
Messier 13 - M13 - Great Hercules Globular Cluster
Messier 92 - M92 - Globular Cluster
Messier 11 - M11 - The Wild Duck Cluster (Open Cluster)
Messier 7 - M7 - The Ptolemy Cluster (Open Cluster)
Messier 6 - M6 - The Butterfly Cluster (Open Cluster)
Messier 4 - M4 - Globular Cluster
Messier 8 - M8 - Lagoon Nebula (Emission Nebula)
Messier 16 - M16 - Eagle Nebula (Emission Nebula with Open Cluster)
Messier 20 - M20 - Trifid Nebula (Emission and Reflection Nebula)

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