Umbra

Umbra, penumbra and antumbra of Earth and images that could be seen at some points in these areas (note: the relative size and distance of the bodies shown are not to scale).
  1. Difference Between Umbra And Penumbra
  2. Www.umbra.com
  3. Umbral Engram
  4. Umbral Engram
Umbra (A) and penumbra (B)

The umbra, penumbra and antumbra are three distinct parts of a shadow, created by any light source after impinging on an opaque object. Assuming no diffraction, for a collimated beam (such as a point source) of light, only the umbra is cast.

These names are most often used for the shadows cast by celestial bodies, though they are sometimes used to describe levels, such as in sunspots.

Umbra[edit]

  • Umbra definition is - a conical shadow excluding all light from a given source; specifically: the conical part of the shadow of a celestial body excluding all light from the primary source.
  • Umbra Lab is developing synthetic aperture radar (SAR) microsatellites to deliver sub-meter resolution imagery as a service. Our space-based radar can capture images day and night regardless of weather conditions, for delivery via an integrated web platform.
  • Umbra definition is - a conical shadow excluding all light from a given source; specifically: the conical part of the shadow of a celestial body excluding all light from the primary source.

1 Lore 2 Skins 3 Trivia 4 Media Umbra, a shadow dragon, appears guarded and reserved at first. However, once a mortal has earned their trust, they show sweet affection and fierce dedication, conjuring shadow and flame to defend their allies. You can unlock skins for this Little Legend by purchasing a Little Legend Egg, which costs 490. Cracking open your egg will grant you a random tier-1.

Umbra, penumbra, and antumbra formed through windows and shutters

The umbra (Latin for 'shadow') is the innermost and darkest part of a shadow, where the light source is completely blocked by the occluding body. An observer within the umbra experiences a total eclipse. The umbra of a round body occluding a round light source forms a right circular cone. As viewed from the cone's apex, the two bodies appear the same size. The distance from the Moon to the apex of its umbra is roughly equal to that between the Moon and Earth: 384,402 km (238,856 mi). Since Earth's diameter is 3.70 times the Moon's, its umbra extends correspondingly farther: roughly 1,400,000 km (870,000 mi).[1]

Penumbra[edit]

The penumbra (from the Latin paene 'almost, nearly') is the region in which only a portion of the light source is obscured by the occluding body. An observer in the penumbra experiences a partial eclipse.An alternative definition is that the penumbra is the region where some or all of the light source is obscured (i.e., the umbra is a subset of the penumbra). For example, NASA's Navigation and Ancillary Information Facility defines that a body in the umbra is also within the penumbra.[2]

Scale diagram of Earth's shadow, showing how the umbral cone extends beyond the orbit of the Moon (the Moon is indicated by the yellow dot).
Earth's umbra, as seen during a partial lunar eclipse

Antumbra[edit]

The antumbra (from Latin ante, 'before') is the region from which the occluding body appears entirely within the disc of the light source. An observer in this region experiences an annular eclipse, in which a bright ring is visible around the eclipsing body. If the observer moves closer to the light source, the apparent size of the occluding body increases until it causes a full umbra.[3]

See also[edit]

References[edit]

  1. ^Pogge, Richard. 'Lecture 9: Eclipses of the Sun & Moon'. Astronomy 161: An Introduction to Solar System Astronomy. Ohio State University. Retrieved July 16, 2015.
  2. ^Event Finding Subsystem Preview Navigation and Ancillary Information Facility.
  3. ^'Eclipses: What Is the Antumbra?'. timeanddate.com. Retrieved 26 May 2019.
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Umbra,_penumbra_and_antumbra&oldid=986023250'

By Konstantin Bikos

The umbra is the dark center portion of a shadow. The Moon's umbra causes total solar eclipses, and the Earth's umbra is involved in total and partial lunar eclipses.

Umbraco

Flowvella. Like any other opaque objects illuminated by a light source, the Moon and the Earth cast shadows into space as they block the sunlight that hits them. Each shadow has 3 different areas: the umbra, the penumbra, and the antumbra.

Umbra

Umbra Definition

The umbra is a shadow's dark core. Imagine a light source and an object casting a shadow. If you are standing within the umbra, you will not be able to see any part of the light source as the object blocks all direct light rays.

The other 2 areas are:

  • Penumbra – the lighter outer part of the shadow.
  • Antumbra – the lighter part of the shadow that begins where the umbra tapers to a point.

When the Earth enters the Moon's shadow, we see a solar eclipse; when the Moon travels through the Earth's shadow, a lunar eclipse occurs. The type of eclipse depends on the type of shadow that is involved.

Moon's Umbra Causes Total Solar Eclipses

If you are within the Moon's umbra and look into the direction of the Sun, you will see a total solar eclipse as the Moon blocks the all of the Sun. On its journey through space, the Moon always casts an umbra. This means that somewhere in space, on the dark side of the Moon, a total solar eclipse is happening right now.

Difference Between Umbra And Penumbra

The reason why solar eclipses are so rare is that the Moon's umbra rarely hits the Earth's surface. Even during a total solar eclipse, the umbra only covers a small area on Earth.

Umbra

As both the Moon and the Earth are in constant motion, the umbra moves across the face of the Earth during the eclipse, so the total phase can usually only be seen along a slim eclipse path. For example, the total solar eclipse on April 8, 2024 will only be visible along a narrow belt stretching across the United States, Mexico, and Canada.

Umbra

How Large Is the Moon's Umbra?

The size of the area on the Earth's surface covered by the Moon's umbra during a total solar eclipse depends, amongst other things, on the Moon's current distance from Earth. The smaller the distance, the larger the umbra.

Www.umbra.com

If the Moon is at its closest to Earth (its perigee) during the eclipse, the Moon appears larger in the sky. In that case, the umbra's path across the Earth's surface typically has a width of roughly 150 km (90 mi) at the Earth's equator. At higher latitudes, the Sun's rays hit the Earth's surface at a shallower angle, so the umbra's size grows accordingly. During some total solar eclipses, the umbra's path width reaches over 1000 km (600 mi) at the poles.

If the eclipse occurs when the Moon's distance is greater, the tip of the Moon's cone-shaped umbra (see illustration) may only just reach the Earth's surface during parts of the eclipse, meaning that its diameter is close to zero. The total phase of the solar eclipse then lasts only a short moment. For example, the total solar eclipse on December 6, 2067 will last only 8 seconds at its maximum point, with partial phases before and after totality. This eclipse will be a hybrid solar eclipse.

If the Moon is close to its apogee, its farthest from Earth, during the eclipse, the umbra does not reach the Earth's surface at all, and it is replaced by the antumbra, producing an annular solar eclipse.

Definition

Earth's Umbra Causes Lunar Eclipses

Like the Moon, Earth always casts an umbra. In fact, we travel through it quite regularly. It is called: night. Every time the Sun goes down, we delve into the darkness created by Earth's umbra. However, as with total solar eclipses, lunar eclipses only occur every so often because they require the Moon to enter the Earth's umbra.

The Earth's umbra is involved in both total and partial lunar eclipses. During a total lunar eclipse, the entire Moon enters the umbra. A partial lunar eclipse occurs when the umbra covers only part of the Moon's surface.

A penumbral lunar eclipse occurs when the Moon enters the Earth's penumbra.

No Umbra During Planet Transits

Umbral Engram

During a planet transit of the Sun, Mercury or Venus pass in front of the Sun, as seen from Earth. Because of their large distance from the Earth, their umbras end a long way before they reach the Earth's surface.

Umbral Engram

This means that we travel through a planet's antumbra during a transit. As the antumbra's diameter increases with growing distance, it is very wide when it reaches Earth, so most planet transits take several hours.