http://www.skyandtelescope.com.au 47by Con Stoitsis METEORSThe three amigos of meteors
Atriooflate-Julyshowerswillkeepobserversontheirtoes.
SKY PHENOMENA
JULY 2017 Australian Eastern Standard Time
1 Jupiter3°southofMoon
2 Juno at opposition
3 Mercury5°southofPollux
4 Earth at aphelion
6 Moon at apogee
7 Saturn3°southofMoon
10 Pluto at opposition
14 Neptune0.9°northofMoon
14 Venus3°northofAldebaran
17 Uranus4°northofMoon
20 Aldebaran0.4°southofMoon
20 Venus3°northofMoon
22 Moon at perigee
25 Mercury 0.9° south of Moon
25 Regulus0.07°southofMoon
26 Mercury1.1°southofRegulus
27 Mars in conjunction with Sun
29 Jupiter3°southofMoon
30 Mercurygreatestelongationeast(27°)JULY 2017
First Quarter 1st, 00:51 UT
Full Moon 9th, 04:07 UT
Last Quarter 16th, 19:26 UT
New Moon 23rd, 09:46 UT
First Quarter 30th, 15:23 UT
Apogee 6th, 04h UT
405,934 km
Perigee 21st, 17h UT
361,236 km
E WNSANTONÍN RÜKL
T
he cold nights of July can be the
most rewarding when it comes
to meteor shower observing.
Both the Southern Delta Aquariids
and Alpha Capricornids showers are at
their peak, and their meteors appear
to radiate from the same part of the
sky with the radiants not too far apart.
Addingtothefunisaminorshower,
thePiscisAustrinids,whichisactiveat
thesametime.
TheAlphaCapricornidshoweris
active from mid-July to mid-August,
withamaximumaroundJuly28–30
andazenithalhourlyrate(ZHR)of5
to 6. What it lacks in numbers is more
thanmadeupforbythespectacular
natureofitsmeteors,astheshower
—whoseparentcometis169/PNEAT
—hasahighpercentageoffireballs
and, on occasion, bolides. The meteors
canbeanycolourbutareoftenyellow.
They move very slowly and often leave
persistent trains that last for minutes.
ThemostfavourableviewoftheAlpha
Capricornidscanbehadanhourortwo
before dawn.
TheSouthernDeltaAquariidsisactive from mid-July to mid-August,
with a maximum (ZHR of 18 to 20)
around July 27–30 — although, unlike
many showers, the Delta Aquariids
lack a very definite peak. Instead, these
medium-speed meteors are active
throughout late-July and early-August.
The meteors appear to radiate from near
the star Delta Aquarii. So like the Eta
AquariidsinMay,theDeltaAquariid
shower favours observers in the
Southern Hemisphere. The hour before
dawnusuallypresentsthebestviewof
the them.
Andfinally,theminormeteor
shower Piscis Austrinids is also active
around July 28 to 30. Its meteors are
usuallyfaintandswift.Don’texpect
morethan2to3perhour,afewhours
before dawn.■CON STOITSISis the director of the
Astronomical Society of Victoria’s comet
and meteor sections.X The radiants for the Southern Delta Aquariids,
Alpha Capricornids and Piscis Austrinids are
close together in the late-July sky.