4071 Five Dots by Franc

This was a puzzle with a superb ending, exploiting a 400 year old theme which seemed to have been created with a Listener crossword in mind.

The first and last letters of the extra words in clues spelt out I DO NOT FEEL OBLIGED TO BELIEVE THAT THE SAME GOD WHO HAS ENDOWED US WITH SENSE, REASON AND INTELLECT HAS INTENDED US TO FORGO THEIR USE, a quotation by Galileo Galilei. Although it does not seem to be in the dictionary of quotations from either Oxford or Chambers, it can be readily identified from Internet sources. Nevertheless, identifying the quotation was not critical to completing the puzzle.

In four cells, Across and Down answers clashed. Several letters from each answer, which would otherwise have been squeezed into the intersecting cell, had to be replaced by dots. The dots represented GANYMEDE, JUPITER, EUROPA and CALLISTO, spelt out by the letters from the intersecting answers. Ganymede, Europa and Callisto are all moons of Jupiter. The distances from the three moons to Jupiter were in approximately the correct proportions.

In the centre row of the grid, the letters GALILE could be seen, with an adjacent blank cell. This cell was to be filled with a dot, representing IO, the fourth moon of Jupiter to be discovered by GALILEO GALILEI between January and March 1610, and this was also positioned at about the correct distance from Jupiter. The I and O of IO therefore completed his name in full, providing a final flourish of which Franc can be proud.

Extra words, and letters not given by wordplay, are indicated with [ ].

Across
1 Largely unsafe [ice-show] turns causing chaos (5)
SNAFU Anagram of UNSAF(E)
4 Baldness of Greek character's sister, see, in [Delhi] (8)
PSILOSIS PSI (Greek character) + SIS (sister), containing LO (see)
10 On account of [overt] force, is he initially clumsy? (6)
OAFISH O/A (on account of) + F (force) + first letters of Is He
12 Scots own fish in [north] channel (7)
LEE-LANE EEL (fish) inside LANE (channel)
13 Poet [Oates] loses special tobacco (4)
BURN BURNS (Poet) less S (special)
14 [Telecine] communication skill - nothing risqué (5)
ORACY O (nothing) + RACY (risque)
16 [Foreign] nobleman's charge for drink (4)
DRAP D (Duke ie nobleman) + RAP (charge)
17 Gypsy [exfoliants] blasted zit (4)
TZI[GANY] Anagram of ZIT (Reduced wordplay)
19 Unbeliever in [elaborate] robbery (7)
ATHEIST AT (in) + HEIST (robbery)
21 Railway siding is [LNER] fabrication (3)
LIE Two meanings
23 Ratify losing part of [Ogilvie] clan (4)
SEAL SEPTAL (of clan), less PT (part)
24 Lowly Japanese in [Burma] get arms (3)
ETA Hidden in gET Arms
26 Tender [lass] ingests drug to race (6)
CAREER CARER (Tender) containing E (drug)
27 Corrupt [Idaho] satirist (6)
[JU]VENAL VENAL (corrupt) (Reduced wordplay)
32 Spot [Gwen] O'Connor, say, given slogan (6)
DESCRY DES (O’Conner, say) + CRY (slogan)
35 This game rating echoes triumphant cry: ["Eureka"] (3)
ELO OLE (triumphant cry), reversed
36 [Devonian] rubber quantity (5)
MASS[EUR] MASS (rubber) (Reduced wordplay)
38 Long Spike [tramped] north (4)
EARN EAR (spike) + N (north)
40 Sister's jolly [Omani] not out of bed (5)
TITTY
41 [Belgian] Red Cross out east to mingle (6)
COMMIX COMMIE (Red) + X (cross), less E (east) (Reduced wordplay)
42 Soak [escargot] in dish (4)
S[CALL]OP SOP (soak) (Reduced wordplay)
43 I [love] indigenous broadcast - not badly sung (6)
IODINE Anagram of INDIGENOUS, less anagram of SUNG
46 [Insect] noise: an ideal kind (5)
HUMAN HUM (noise) + AN
48 This study of [equatorial] schools with Lomé involves my college too (8)
CETOLOGY Anagram of MY COLLEGE TOO, less anagram of LOMÉ
50 A fellow artist in retreat by Arabian [vine] tree (7)
ARAROBA A + BO (fellow) _ RA (artist), all reversed, after AR (Arabian)
51 Alcohol damaged [erotic] idol (4)
DIOL Anagram of IDOL
52 Stars' agreement with DA could make Dr say "Nasty [twit]!" (8)
SYNASTRY Anagram of DR SAY NASTY less DA
53 Finished [hip-bath], repaired after losing mixer's top (5)
ENDED MENDED (fixed), less M (first letter of MIXER)

Down

1 Shoot old [Abba] boy in the bottom! (6)
SOBOLE OB (old boy) in SOLE (bottom)
2 [Tales] of sailors in, one hears, badly-behaved state (8)
NAUTICAL First two syllables being a homophone of NAUTY, + CAL (state)
3 [Thai,] in condition, turned back over (4)
FINI IN + IF (condition), all reversed
4 [Helen] Richardson's first in stage expression (6)
PHRASE R (first letter of RICHARDSON) in PHASE (stage)
5 [Elegant] Spanish man swallows dead woodlouse (6)
SLATER SR (Senor ie Spanish man) containing LATE (dead)
6 [Stable] Romanian currency returns the pound (3)
LEY YE (The) + L (pound), all reversed
7 Nostalgic number [American] soldier takes to heart (5)
OLDIE Hidden in sOLDIEr
8 Stone [mound] pair of archaeologists found in climbing headland (6)
SARSEN AR (two letters from ARchaeologist) inside NESS (headland), reversed
9 Drawing of Greek [exile,] character overcome by tide (5)
SEPIA PI (Greek character) inside SEA (tide)
11 [Good] fish? Rather old! (5)
SO[MEDE]LE SOLE (fish) (Reduced wordplay)
15 Capital [ombu] tea (4)
CHA[PITER] CHA (tea) (Reduced wordplay)
18 Enthusiast [decides] to laze around (6)
ZEALOT Anagram of TO LAZE
20 Twelve [Watchet] residents arrest slippery juvenile (5)
ELVER Hidden in TwELVE Residents)
22 Mother-to-be shows rather formal [hairdo] in Brazilian state (9)
PRIMIPARA PRIM (rather formal) + I’ (in) + PARÁ (Brazilian state)
25 Sailor's [off] to get round pitching (7)
TARRING TAR (Sailor) + RING (round)
28 Old banks I had [hitherto] pronounced as sharp-sighted (8)
LYNX-EYED Homophone of LINKS + I’D (obsolete word for “banks” + I had)
29 Reportedly, merry kings [abhor] losing hearts to immoral women (7)
GEISHAS Homophone of GAY SHAHS (merry kings), less H (hearts)
30 Alto's in [song] arranged for campesinos? (7)
LATINOS Anagram of ALTO’S IN
31 Use this to get a cut in part of the [Euro] Stocks (5)
ESTOC Hidden in thE STOCks
33 Gingili oil plant's husks are [not] powdered (4)
SEME End letters of SE(SA)ME (Gingili oil plant)
34 Will's awry over [Dutch] deal, say, for source of dye (7)
CAMWOOD CAM (Shakespearian word for “awry” sv kam) + WOOD (deal being an example of a type of wood)
37 Obscurity shown by [one-horse] settlement? (5)
[OPA]CITY CITY (settlement) (Reduced wordplay)
39 [Wali] to hide narrow knife (5)
B[ISTO]URY BURY (to hide) (Reduced wordplay)
44 Dare to resolve grievous [error] (4)
DEAR Anagram of DARE
45 [Dolgellau] junction approval has come at last (4)
NODE NOD (approval) _ E (last letter of COME)
47 Husband sources of manganese, [uridines] and nitrates (3)
MAN First letters of Manganese And Nitrates
49 [Saline] pool found in limestone block (3)
LIN Middle letters of CLINT (limestone block)