Definition of umbra in English:


nounPlural umbrae, Plural umbras

  • 1The fully shaded inner region of a shadow cast by an opaque object, especially the area on the earth or moon experiencing the total phase of an eclipse.

    Compare with penumbra
    • ‘During the partial stage the increasing penumbral penetration is not noticeable on a minute-to-minute basis, but as the umbra approaches things start to happen fast.’
    • ‘First, the Earth stopped turning relative to the sun, and the moon parked itself on the dark side, a little outside the umbra.’
    • ‘When the Moon is fully immersed in the umbra a total lunar eclipse occurs.’
    • ‘If the Moon completely enters the umbra, a total lunar eclipse occurs.’
    • ‘Soft shadows will create more realistic lighting effects, since this type of shadow more closely resembles shadows in the real world, and cast both an umbra an a penumbra.’
    • ‘But the penumbra is so faint that it cannot be recognized until just before the Moon enters the Earth's dark central shadow, the umbra.’
    • ‘Long, thin filaments radiate from the umbra into a brighter surrounding region called the penumbra.’
    • ‘A penumbral eclipse, sometimes called an appulse, occurs when the Moon misses the Earth's umbra but passes through its penumbra or secondary shadow.’
    • ‘Also, because the Earth has an atmosphere, the Moon never really disappears from view, since some light is scattered and bent by the atmosphere and still reaches the Moon's surface, even when it is in the umbra, or total shadow.’
    • ‘For an observer standing between the Moon and the umbra cone summit the eclipse is total.’
    • ‘The total eclipse begins when the Moon is fully inside the umbra.’
    • ‘At mid-totality, the Moon's southern limb is a mere 0.7 arc-minutes from the umbra's centre.’
    • ‘If you were in a spaceship and you passed through the Earth's umbra you would not be able to see any part of the Sun.’
    • ‘The Moon can then pass through a part of the umbra (region of total shadow) and then there is a partial eclipse.’
    • ‘The total eclipse begins when the Moon is fully inside the umbra, but it won't be completely blacked out.’
    • ‘How much the moon is dimmed depends on whether it passed through the penumbra or the darkest part of the shadow, the umbra.’
    • ‘And by the time all of the moon is inside the umbra, at 5: 14 am, it will have changed colour, looking dim and amber to copper.’
    • ‘The umbra is a central cone of darkness which tapers away from the Earth or Moon.’
    • ‘Our planet's shadow has two parts, a dark inner core called the umbra and a pale outer fringe called the penumbra.’
    • ‘While it is entirely within the umbra the lunar disk brightness drops to about one part in 5,000 that of the near-full moon, and so it can still be seen.’
    1. 1.1Astronomy The dark central part of a sunspot.
      • ‘The fact that he could see the sunspots with the naked eye and that he could make out the umbrae and penumbrae of the spots suggest that they must have been extremely large.’
      • ‘The darkest, central region of a sunspot, called the umbra, features tightly bundled magnetic field lines.’
      • ‘Each sunspot consists of a dark central umbra, which is estimated to have a temperature in the region of 4000°C, and a surrounding penumbra, at a temperature in the region 5000°C.’
      • ‘The penumbra is the transition from the photosphere to the umbra.’
      • ‘When viewed through a telescope, sunspots have a dark central region known as the umbra, surrounded by a somewhat lighter region called the penumbra.’
      • ‘The strongest solar magnetic fields, up to 4000 gauss, are found within the umbra.’
  • 2literary mass noun Shadow or darkness.

    ‘an impenetrable umbra seemed to fill every inch of the museum’
    • ‘Reacting, the Viking threw up his shield, disappearing into an umbra of flame.’
    • ‘How about cleverly distracting from under-eye umbra with some beauty department illusions?’
    • ‘Not once did she ask if he knew where they were going; and now, with a nettle laced gully yawning out past any shadowed umbra before them, that suddenly appeared very naive.’
    • ‘Outlined against the setting sun, the silhouette took on a strangely surreal beauty, as if a shadow's penumbra and umbra were fused together.’
    silhouette, outline, shape, contour, profile
    View synonyms


Late 16th century (denoting a phantom or ghost): from Latin, literally ‘shade’.