The Rosette Nebula

Inside the nebula lies an open cluster of bright young stars designated NGC 2244. These stars formed about four million years ago from the nebular material and their stellar winds are clearing a hole in the nebula's center, insulated by a layer of dust and hot gas. Ultraviolet light from the hot cluster stars causes the surrounding nebula to glow. The Rosette Nebula spans about 100 light-years across, lies about 5000 light-years away, and can be seen with a small telescope towards the constellation of the Unicorn (Monoceros).

Image Credit & Copyright: Brian Lula
Explanation from: http://apod.nasa.gov/apod/ap110214.html

All the water on Europa

How much of Jupiter's moon Europa is made of water? A lot, actually. Based on the Galileo probe data acquired during its exploration of the Jovian system from 1995 to 2003, Europa posses a deep, global ocean of liquid water beneath a layer of surface ice. The subsurface ocean plus ice layer could range from 80 to 170 kilometers in average depth. Adopting an estimate of 100 kilometers depth, if all the water on Europa were gathered into a ball it would have a radius of 877 kilometers. To scale, this intriguing illustration compares that hypothetical ball of all the water on Europa to the size of Europa itself (left) - and similarly to all the water on planet Earth. 

With a volume 2-3 times the volume of water in Earth's oceans, the global ocean on Europa holds out a tantalizing destination in the search for extraterrestrial life in our Solar System

Image Credit & Copyright: Kevin Hand, Jack Cook and Howard Perlman
Explanation from: http://apod.nasa.gov/apod/ap120524.html

Home from Above

This view of Earth’s horizon as the sunsets over the Pacific Ocean was taken by an Expedition 7 crewmember onboard the International Space Station (ISS). Anvil tops of thunderclouds are also visible.

ISS, Orbit of the Earth

21 July, 2003

Image Credit: NASA

Haboob over Australia

 

A white shelf cloud caps brownish dirt from a dust storm, or haboob, as it travels across the Indian Ocean near Onslow on the Western Australia coast

Onslow, Western Australia, Australia

January 9, 2013

Images Credit: Brett Martin

Earth's Location in the Universe

Earth → Solar System → Solar Interstellar Neightborhood → Milky Way Galaxy → Local Galactic Group → Virgo Supercluster → Observable Universe → Universe → Unknown (our Universe might be a part of Multiverse)

Earth - 12,700 km in diameter - Our planet

Geospace - 63,000 km Sunward side; - 6,300,000 km trailing side - The space dominated by Earth's magnetic field

Orbit of the Moon - 770,000 km across - The average diameter of the orbit of the Moon relative to the Earth

Earth's Orbit - 300 million km across (2 AU) - The average diameter of the orbit of the Earth relative to the Sun. Contains the Sun, Mercury and Venus

Inner Solar System - 6 AU across - Contains the Sun, the inner planets (Mercury, Venus, Earth and Mars) and the asteroid belt

Outer Solar System - 60 AU across - Surrounds the inner Solar System; comprises the outer planets (Jupiter, Saturn, Uranus and Neptune)

Kuiper Belt - 96 AU across - Belt of icy objects surrounding the outer solar system. Contains the dwarf planets Pluto, Haumea and Makemake

Heliosphere - 160 AU across - Maximum extent of the Solar wind and the interplanetary medium

Scattered Disk - 200 AU across - Region of sparsely scattered icy objects surrounding the Kuiper belt. Contains the dwarf planet Eris

Oort Cloud - 100,000–200,000 AU across (2–4 light-years) - Spherical shell of over a trillion comets

Solar System - 4 light-years across - Our home planetary system. At this point, the Sun's gravity gives way to that of surrounding stars

Local Interstellar Cloud - 30 light-years across - Interstellar cloud of gas through which the Sun and a number of other stars are currently travelling

Local Bubble - 210–815 light-years across - Cavity in the interstellar medium in which our Sun and a number of other stars are currently travelling. Caused by a past supernova

Gould Belt - 3,000 light-years across - Ring of young stars through which our Sun is currently travelling

Orion Arm - 10,000 light-years in length - The spiral arm of the Milky Way Galaxy through which our Sun is currently travelling

Orbit of the Solar System - 56,000 light years across - The average diameter of the orbit of the Sun relative to the Galactic Center. Our Sun's orbital radius is roughly 28,000 light years, or slightly over half way to the galactic edge. One orbital period of our Solar System lasts between 225 and 250 million years

Milky Way Galaxy - 100,000 light-years across - Our home galaxy, composed of 200 billion to 400 billion stars and filled with the interstellar medium

Milky Way Subgroup - 2.74 million light-years across (0.84 megaparsecs) - The Milky Way and those satellite galaxies gravitationally bound to it, such as the Sagittarius Dwarf, the Ursa Minor Dwarf and the Canis Major Dwarf. Cited distance is the orbital diameter of the Leo T Dwarf galaxy, the most distant galaxy in the Milky Way subgroup

Local Group - 3 megaparsecs across - Group of at least 47 galaxies. Dominated by Andromeda Galaxy (the largest), The Milky Way and Triangulum; the remainder are small dwarf galaxies

Virgo Supercluster - 33 megaparsecs across - The supercluster of which our Local Group is a part; comprises roughly 100 galaxy groups and clusters

Pisces-Cetus Supercluster Complex - 300 megaparsecs across - The galaxy filament of which the Virgo Supercluster is a part

Observable Universe - 28,000 megaparsecs across - The large-scale structure of the Universe consists of more than 100 billion galaxies, arranged in millions of superclusters, galactic filaments, and voids, creating a foam-like superstructure

Universe - Minimum of 28,000 megaparsecs - Beyond the observable Universe lies the unobservable regions where no light from those regions has reached the Earth yet. No information is available about the region, as light is the fastest travelling medium of information. However, since there is no reason to suppose different natural laws, the universe is likely to contain more galaxies in the same foam-like superstructure

Beyond - Size Unknown - Our universe might be a part of multiverse, omniverse, and/or other hypothetical concepts


Explanation of units:

• 1 AU or Astronomical Unit is the distance between the Earth and the Sun, or 150 million km. Earth's orbital diameter is twice its orbital radius, or 2 AU

• One light-year is the distance light travels in a year; equivalent to 9.46 trillion km or 63,200 AU

• A parsec is 3.26 light-years

• One megaparsec is equivalent to one million parsecs or 3.26 million light-year

Images Credit: Andrew Z. Colvin
Explanation from: http://en.wikipedia.org