Life on Mars

For centuries people have speculated about the possibility of life on Mars due to the planet's proximity and similarity to Earth. Although there has been much speculation, to date there has never been any proof of life existing on Mars. However, cumulative evidence is now building that Mars once was habitable.

Serious searches for evidence of life began in the 19th century, and they continue today via telescopic investigations and landed missions. While early work focused on phenomenology and bordered on fantasy, modern scientific inquiry has emphasized the search for water, chemical biosignatures in the soil and rocks at the planet's surface, and biomarker gases in the atmosphere.

Mars is of particular interest for the study of the origins of life because of its similarity to the early Earth. This is especially so since Mars has a cold climate and lacks plate tectonics or continental drift, so it has remained almost unchanged since the end of the Hesperian period. At least two thirds of Mars's surface is more than 3.5 billion years old, and Mars may thus hold the best record of the prebiotic conditions leading to abiogenesis, even if life does not or has never existed there. It remains an open question whether life currently exists on Mars or has existed there in the past, and fictional Martians have been a recurring feature of popular entertainment of the 20th and 21st centuries.

Mars

Mars is the fourth planet from the Sun and the second smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is often referred to as the "Red Planet" because the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth.

The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, as is the tilt that produces the seasons. Mars is the site of Olympus Mons, the largest volcano and second-highest known mountain in the Solar System, and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature. Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars trojan.

Life

Life is a characteristic distinguishing physical entities having biological processes (such as signaling and self-sustaining processes) from those that do not, either because such functions have ceased (death), or because they lack such functions and are classified as inanimate. Various forms of life exist such as plants, animals, fungi, protists, archaea, and bacteria. The criteria can at times be ambiguous and may or may not define viruses, viroids or potential artificial life as living. Biology is the primary science concerned with the study of life, although many other sciences are involved.

Throughout history there have been many theories about life including materialism, hylomorphism and vitalism. Even today it is a challenge for scientists and philosophers to define life. The smallest contiguous unit of life is called an organism. Organisms are composed of one or more cells, undergo metabolism, maintain homeostasis, can grow, respond to stimuli, reproduce (either sexually or asexually) and, through evolution, adapt to their environment in successive generations. A diverse array of living organisms can be found in the biosphere of Earth, and the properties common to these organisms are a carbon- and water-based cellular form with complex organization and heritable genetic information.

David Bowie

David Robert Jones (8 January 1947 – 10 January 2016), known as David Bowie (/ˈboʊ.i/), was an English singer, songwriter, multi-instrumentalist, record producer, painter, and actor. He was a figure in popular music for over five decades, and was considered by critics and musicians as an innovator, particularly for his work in the 1970s. His career was marked by reinvention and visual presentation, and his music and stagecraft significantly impacted popular music. During his lifetime, he sold an estimated 140 million records worldwide. In the UK, he was awarded nine platinum album certifications, eleven gold and eight silver, and released eleven number-one albums. In the US, he received five platinum and seven gold certifications. He was inducted into the Rock and Roll Hall of Fame in 1996.

New York

New York is a state in the Northeastern United States and is the United States' 27th-most extensive, fourth-most populous, and seventh-most densely populated state. New York is bordered by New Jersey and Pennsylvania to the south and Connecticut, Massachusetts, and Vermont to the east. The state has a maritime border in the Atlantic Ocean with Rhode Island, east of Long Island, as well as an international border with the Canadian provinces of Quebec to the north and Ontario to the west and north. The state of New York, with an estimated 19.8 million residents in 2015, is often referred to as New York State to distinguish it from New York City, the state's most populous city and its economic hub.

With an estimated population of nearly 8.5 million in 2014, New York City is the most populous city in the United States and the premier gateway for legal immigration to the United States. The New York City Metropolitan Area is one of the most populous urban agglomerations in the world. New York City is a global city, exerting a significant impact upon commerce, finance, media, art, fashion, research, technology, education, and entertainment, its fast pace defining the term New York minute. The home of the United Nations Headquarters, New York City is an important center for international diplomacy and has been described as the cultural and financial capital of the world, as well as the world's most economically powerful city. New York City makes up over 40% of the population of New York State. Two-thirds of the state's population lives in the New York City Metropolitan Area, and nearly 40% live on Long Island. Both the state and New York City were named for the 17th century Duke of York, future King James II of England. The next four most populous cities in the state are Buffalo, Rochester, Yonkers, and Syracuse, while the state capital is Albany.