Size It Up

ALL ANSWERS · SPACE · DAILY No. 17 · SEPTEMBER 20, 2026

Size It Up Space answer: September 20

The five Space silhouettes for September 20, with the true sizes. If you have not played yet, this page is a spoiler — play these five first, then come back to argue with the numbers.

Day 17 ran from Mimas (396.4 km) to Mars (6,779 km). The widest gap was round 3, Mimas against Tethys, at 2.7×; the closest call was round 4, Iapetus against Rhea, only 1.0× apart — the kind of round that separates a 90 from a 60.

  1. ROUND 1

    Moon (Earth’s moon · mean diameter) vs Titania (Uranus’s moon · mean diameter)

    Titania · reference · 1,578 km
    Moon · true diameter · 3,475 km

    2.2× wider than Titania

    Moon, a moon of Earth, has a mean diameter of about 3,474.8 km. This is the body’s size, not an orbital distance.

  2. ROUND 2

    Mercury (mean diameter) vs Mars (mean diameter)

    Mars · reference · 6,779 km
    Mercury · true diameter · 4,879 km

    1.4× shorter than Mars

    Mercury has a mean diameter of about 4,878.8 km. This is the body’s size, not an orbital distance.

  3. ROUND 3

    Mimas (Saturn’s moon · mean diameter) vs Tethys (Saturn’s moon · mean diameter)

    Tethys · reference · 1,062 km
    Mimas · true diameter · 396.4 km

    2.7× shorter than Tethys

    Mimas, a moon of Saturn, has a mean diameter of about 396.4 km. This is the body’s size, not an orbital distance.

  4. ROUND 4

    Iapetus (Saturn’s moon · mean diameter) vs Rhea (Saturn’s moon · mean diameter)

    Rhea · reference · 1,527 km
    Iapetus · true diameter · 1,469 km

    1.0× shorter than Rhea

    Iapetus, a moon of Saturn, has a mean diameter of about 1,468.6 km. This is the body’s size, not an orbital distance.

  5. ROUND 5

    Dione (Saturn’s moon · mean diameter) vs Enceladus (Saturn’s moon · mean diameter)

    Enceladus · reference · 504.2 km
    Dione · true diameter · 1,123 km

    2.2× wider than Enceladus

    Dione, a moon of Saturn, has a mean diameter of about 1,122.8 km. This is the body’s size, not an orbital distance.

Beat these tomorrow

Every round is worth up to 100 points: within 6% of the true size scores 100, half or double scores 45, five times off scores zero. The daily puzzle is the same five for everyone and refreshes at midnight in your time zone; if you want more than five, Size It Up Unlimited draws fresh pairs from the whole library for as long as you like.

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MixedAnimals, planets and everyday things. AnimalsLength, height or wingspan — every round names the axis. GeographyEast–west or north–south span, never area. Pop CultureCheck the version. Compare the measured dimension. VehiclesLength end to end, or height for the ones that stand upright. DinosaursCompare estimated body length, from snout to tail tip. SpaceCompare body diameter. Rings and orbital distances are excluded. Everyday ObjectsLength, height or width — every round names the axis. InsectsBody length or wingspan — read the named measurement. LandmarksRead the named height, length or main span — including its endpoints. Food & DrinkRead the selected size and axis — length, diameter or container height.
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