ALL ANSWERS · SPACE · DAILY No. 14 · SEPTEMBER 17, 2026

Size It Up Space answer: September 17

The five Space silhouettes for September 17, 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 14 ran from Umbriel (1,169 km) to Jupiter (139,800 km). The widest gap was round 5, Europa against Earth, at 4.1×; the closest call was round 1, Iapetus against Titania, only 1.1× apart — the kind of round that separates a 90 from a 60.

  1. ROUND 1

    Iapetus (Saturn’s moon · mean diameter) vs Titania (Uranus’s moon · mean diameter)

    Titania · reference · 1,578 km
    Iapetus · true diameter · 1,469 km

    1.1× shorter than Titania

    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.

  2. ROUND 2

    Io (Jupiter’s moon · mean diameter) vs Ganymede (Jupiter’s moon · mean diameter)

    Ganymede · reference · 5,262 km
    Io · true diameter · 3,643 km

    1.4× shorter than Ganymede

    Io, a moon of Jupiter, has a mean diameter of about 3,643 km. This is the body’s size, not an orbital distance.

  3. ROUND 3

    Umbriel (Uranus’s moon · mean diameter) vs Pluto (mean diameter)

    Pluto · reference · 2,377 km
    Umbriel · true diameter · 1,169 km

    2.0× shorter than Pluto

    Umbriel, a moon of Uranus, has a mean diameter of about 1,169.4 km. This is the body’s size, not an orbital distance.

  4. ROUND 4

    Neptune (mean diameter) vs Jupiter (mean diameter)

    Jupiter · reference · 139,800 km
    Neptune · true diameter · 49,240 km

    2.8× shorter than Jupiter

    Neptune has a mean diameter of about 49,244 km. This is the body’s size, not an orbital distance.

  5. ROUND 5

    Europa (Jupiter’s moon · mean diameter) vs Earth (mean diameter)

    Earth · reference · 12,740 km
    Europa · true diameter · 3,122 km

    4.1× shorter than Earth

    Europa, a moon of Jupiter, has a mean diameter of about 3,121.6 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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