Australian Sky & Telescope - May 2018

http://www.skyandtelescope.com.au 47

by Con Stoitsi METEORS

Mid-year meteors

on display

M

eteoractivityingeneralis

highestinMayandJunefrom

the Southern Hemisphere, with

manyminormeteorshowersactive.

Unfortunately, this year the Moon

willgreatlyaffecttheseshowers,and

theirzenithalhourlyrate(ZHR)—

the theoretical maximum number of

meteorthatcanbeseenatthezenith

(ie.lookingthroughtheleastamountof

sky) — will be reduced.

TheEtaAquariidsareactivefrom

mid-ApriltoMay,peakingonthe

morningoftheMay6thisyear,witha

modestZHRof5to10meteorsforecast.

This shower generally produces swift

meteorsofyellowcolourandpersistent

trainsareoftenrecorded.Startyour

observations after 3:00am.

Peak sporadic meteor rates occur

during May and June. Sporadics are

random meteors not associated with

anyparticularshower,andarebestbeen

at4:00amlocaltime,whenourpartof

the Earth is facing the same direction

asitstravellinginitsorbitaround

theSun.Thus,notonlyaremeteors

sweptupwhichareheadingtowardthe

Earth, but the movement of the Earth

aroundtheSunenablesittocatchup

with some of the slower meteors and

pull them in. The corollary is that rates

areusuallylowestintheeveningwhen

we’refacingawayfromthedirectionof

the Earth’s travel.

■CON STOITSISis director of the

Astronomical Society of Victoria’s comet

and meteor sections. You can follow him

on Twitter@vivstoitsis

to pages 56-59 for a full run-down of

what to expect and how to study the

planet’s cloud belts, Great Red Spot and

moons. And look for our Moon nearby

on May 27/28 and June 23/24.

Not to be outdone by its larger

sibling, Saturn (mag. 0.3 and 18 ̋

inmid-May,0.0and18.4 ̋atJune’s

end)willreachoppositiononJune27.

Like Jupiter, it will be visible all night

around this time, and will make an

idealtargetforobservationthrough

eventhesmallestoftelescopes.The

planet’srings,withtheirCassini

Division,willbeprominentandeasy

tospot.Saturnwillstayclosetothe

globular star cluster, Messier 22,

duringMayandJune,andwillhave

closeencounterswiththeMoonon

May4andJune1.

Finally,ourplanetwillreachthe

southern winter solstice(where has

theyeargone?)onJune21.Thewinter

solsticeforusiswhentheSunisatits

most northerly declination (+23.5°)

andthehoursofdaylightareshortest.

In the Northern Hemisphere the

oppositeholdstrueatthistimeofyear,

ofcourse,withtheSunbeingnicean

dhighintheskyandwiththehoursof

daylightlongestatthissolstice.

P. HORÁLEK/ESO

MAY

1 Jupiter4°southofMoon

4 Venus7°northofAldebaran

5 Saturn1.7°southofMoon

6 Mars3°southofMoon

9 Jupiter at opposition

10 Neptune2°northofMoon

13 Mercury2°southofUranus

14 Uranus5°northofMoon

14 Mercury2°northofMoon

16 Aldebaran 1.2° south of Moon

18 Venus5°northofMoon

20 Moon8°southofPollux

28 Jupiter4°southofMoon

JUNE

1 Saturn 1.6° south of Moon

3 Mars3°southofMoon

5 Jupiter 0.9° north of Alpha Librae

6 Mercury in superior conjunction

9 Venus5°southofPollux

10 Uranus5°northofMoon

16 Venus2°northofMoon

21 Solstice

24 Jupiter 4° south of Moon

26 Mercury5°southofPollux

27 Saturn at opposition

28 Saturn 1.8° south of Moon

29 Mars stationary

MAY

JUNE

SKY PHENOMENA (dates in AEST) LUNAR PHENOMENA

Last Quarter ...... 8th, 02:09 UT

New Moon ...... 15th, 11:48 UT

First Quarter ...... 22nd, 03:49 UT

Full Moon ...... 29th, 14:20 UT

Apogee ...... 6th, 01h UT, 404,457 km

Perigee ...... 17th, 21h UT, 363,776 km

Last Quarter ...... 6th, 18:42 UT

New Moon ...... 13th, 19:43 UT

First Quarter ...... 20th, 10:51 UT

Full Moon ...... 28th, 04:53 UT

Apogee ...... 2nd, 17h UT, 405,317 km

Perigee ...... 15th, 00h UT, 359,503 km

Apogee ...... 30th, 03h UT, 406,061 km

Despite adverse lunar lighting, it’s still a great time for meteors.