Australian Sky & Telescope - June 2018

SOUTHPOLE:ESA/DLR/FUBERLIN/BILLDUNFORD;ALBEDOMARKINGS:DAMIANPEACH/G

REGG

DINDERMAN (

S&T

); APPARITION: ALPO; HELLAS: ESA / DLR / FU BERLIN / CC BY-SA 3.0 IGO

COME CLOSER As it approaches Earth, Mars will swell from a small apparent disk to a

maximum diameter of 24.3′′ on July 31, the date of closest approach. Opposition occurs on

July 27. The images show Mars at 0h UT, with the planet’s declination and distance from the

Sun noted in astronomical units (au). South is up.

MIGHTY BIG HIT Hellas is the largest, best-preserved

impact structure on Mars. This detail shows the transition

between the rim (top left) and frosty basin loor (bottom).

S

Date

Diam

Dec

AU

Feb. 12

6 ′′

–23.4

1.566

Mar. 25

8 ′′

–23.5

1.173

Apr. 20

10 ′′

–23.4

0.938

May 9

12 ′′

–22.4

0.781

July 31

24.3′′

–25.8

0.385

Oct. 31

12 ′′

–16.8

0.781

Nov. 21

10 ′′

–11.7

0.932

Dec. 21

8 ′′

–3.5

1.169

Feb. 6

6 ′′

9.8

1.570

MARS CALENDAR

May 22

Equinox on

Mars. The

planet shines at

magnitude –1.0,

with a diameter

of 13.9′′.

June 28

Retrograde

(westward)

motion begins.

Mars shines at

magnitude –2.0,

with a diameter

of 20.2′′.

July 27

Mars reaches

opposition.

Mars shines at

magnitude –2.8,

with a diameter

of 24.3′′.

July 31

Mars makes

its closest

approach to

Earth.

Aug. 28

Retrograde

motion ends,

direct (eastward)

motion resumes.

Mars shines at

magnitude –2.2,

with a diameter

of 21.6′′.

Sept. 16

Mars is at

perihelion. The

planet shines at

magnitude –1.7,

with a diameter

of 18.3′′.

Oct. 16

Solstice on

Mars. The

planet shines at

magnitude –0.9,

with a diameter

of 13.6′′.

http://www.skyandtelescope.com.au 39