Definition of Deep Space

Any region in space outside the solar system.

Hubble Ultra-Deep Field

The Hubble Ultra-Deep Field (HUDF) is an image of a small region of space in the constellation Fornax, containing an estimated 10,000 galaxies.

The original release was combined from Hubble Space Telescope data accumulated over a period from September 24, 2003, through to January 16, 2004.

Looking back approximately 13 billion years (between 400 and 800 million years after the Big Bang) it has been used to search for galaxies that existed at that time.


The Hubble Ultra-Deep Field

In August and September 2009 the HUDF field was observed at longer wavelengths (1.0 to 1.6 micrometers) using the infrared channel of the recently attached Wide Field Camera 3 (WFC3) instrument.

When combined with existing HUDF data, astronomers were able to identify a new list of potentially very distant galaxies. Smaller than a 1 mm by 1 mm square of paper held at 1 meter away, and equal to roughly one twenty-six-millionth of the total area of the sky.

In September 25, 2012, NASA released a further refined version of the Ultra-Deep Field dubbed the eXtremeDeep Field (XDF). The XDF reveals galaxies that span back 13.2 billion years in time, revealing a galaxy theorized to be formed only 450 million years after the big bang event.

In June 3, 2014, NASA released the Hubble Ultra-Deep Field image composed of, for the first time, the full range of ultraviolet to near-infrared light.

In January 23, 2019, released an even deeper version of the infrared images of the Hubble Ultra Deep Field obtained with the WFC3 instrument, named the ABYSS Hubble Ultra Deep Field.

The new images improve the previous reduction of the WFC3/IR images, including careful sky background subtraction around the largest galaxies on the field of view. After this update, some galaxies were found to be almost twice as big as previously measured.


The ABYSS Hubble Ultra Deep Field.

Deep-sky Object

Deep-sky object is a term designating any astronomical object that is not an individual star or Solar System object (such as Sun, Moon, planet, comet, etc.).

The classification is used for the most part by amateur astronomers to denote visually observed faint naked eye and telescopic objects such as star clusters, nebulae and galaxies.

This distinction is practical and technical, implying a variety of instruments and techniques appropriate to observation, and does not distinguish the nature of the object itself.

Classifying non-stellar astronomical objects began soon after the invention of the telescope. One of the earliest comprehensive lists was Charles Messier's 1774 Messier catalogue, which included 103 "nebulae" and other faint fuzzy objects he considered a nuisance since they could be mistaken for comets.

As telescopes improved these faint nebulae would be broken into more descriptive scientific classifications such as interstellar clouds, star clusters, and galaxies.

There are many astronomical object types that come under the description of deep-sky objects.

Since the definition is objects that are non-Solar System and non-stellar the list includes.

Star clusters

Open clusters

Globular clusters

Star clusters are very large groups of stars. Two types of star clusters can be distinguished: globular clusters are tight groups of hundreds to millions of old stars which are gravitationally bound, while open clusters, more loosely clustered groups of stars, generally contain fewer than a few hundred members, and are often very young.


Globular Cluster Messier 80


Open Cluster NGC 3572


Bright nebulae

Emission nebulae

Reflection nebulae

Dark nebulae

Planetary nebulae

A nebula (Latin for 'cloud' or 'fog'. nebulae, nebulæ, or nebulas) is an interstellar cloud of dust, hydrogen, helium and other ionized gases. Most nebulae are of vast size; some are hundreds of light-years in diameter.

A nebula that is barely visible to the human eye from Earth would appear larger, but no brighter, from close by. 

Although denser than the space surrounding them, most nebulae are far less dense than any vacuum created on Earth – a nebular cloud the size of the Earth would have a total mass of only a few kilograms.

Nebulae are often star-forming regions, such as in the "Pillars of Creation" in the Eagle Nebula. In these regions the formations of gas, dust, and other materials "clump" together to form denser regions.


Pillars of Creation


A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. The word galaxy is derived from the Greek galaxias (γαλαξίας), literally "milky", a reference to the Milky Way.

Galaxies range in size from dwarfs with just a few hundred million stars to giants with one hundred trillion stars, each orbiting its galaxy's center of mass.

Galaxies are categorized according to their visual morphology as elliptical, spiral, or irregular.

Many galaxies are thought to have supermassive black holes at their centres.



Deep Space Exploration

Deep space exploration is the branch of astronomy, astronautics and space technology that is involved with exploring the distant regions of outer space.

Physical exploration of space is conducted both by human spaceflights (deep-space astronautics) and by robotic spacecraft.

At present the furthest space probes mankind has constructed and launched from Earth is Voyager 1, which was announced on December 5, 2011, to have reached the outer edge of the Solar system, and entered interstellar space on August 25, 2012. And Voyager 2 entered interstellar space on November 5th 2018.

Deep space exploration further than these vessel's capacity is not yet possible due to limitations in the space-engine technology currently available.

 Some of the best candidates for future deep space engine technologies include anti-matter, nuclear power and beamed propulsion.

The latter, beamed propulsion, appears to be the best candidate for deep space exploration presently available, since it uses known physics and known technology that is being developed for other purposes.