The Universe is defined as the summation of all particles and energy that exist and the space-time in which all events occur. Based on observations of the portion of the universe that is observable, physicists attempt to describe the whole of space-time, including all matter and energy and events which occur, as a single system corresponding to a mathematical model.
The scientific theory which describes the origin and evolution of the universe is Big Bangcosmology, which describes the expansion of space from an extremely hot and dense state of unknown characteristics. The universe underwent a rapid period of cosmic inflation that flattened out nearly all initial irregularities in the energy density; thereafter the universe expanded and became steadily cooler and less dense. Minor variations in the distribution of mass resulted in hierarchical segregation of the features that are found in the current universe; such as clusters and superclusters of galaxies. There are more than one hundred billion (1011) galaxies in the universe,[1] each containing hundreds of billions of stars, with each star containing about 1057atoms of hydrogen.
This year's Perseid meteor shower on August 11-14 is predicted to be one of the best in recent years, and if this awesome trailer from "MeteorWatch" organizer Adrian West doesn't get you excited, then nothing will! Who knew meteors could be such a heart-pumping thrill ride! If you haven't heard of MeteorWatch, it is a [...]
JPL issued a press release today with an update that mission controllers have still not heard from the hibernating Spirit rover. Even though the rover is experiencing one of Mars' harshest winters since the rovers arrived, the rover team has begun an active "paging" technique called 'sweep and beep' in an effort to communicate with [...]
Here's some doses of coolness and craziness for your Friday. This top image is one of the latest from the HiRISE camera on the Mars Reconnaissance Orbiter, and shows what looks like a target on the Red Planet. Researchers from the HiRISE team aren't sure yet whether this is two impacts — one impact that [...]
"Water cycle on the Moon" is a phrase that many people – including lunar scientists – were never expecting to hear. This surprising new finding of ubiquitous water on the surface of the Moon, revealed and confirmed by three different spacecraft last year, has been one of the main topics of recent discussion and study [...]
Our Universe 
