A bicycle (sometimes written as bike) is a human-powered, two-wheeled vehicle that uses momentum, force and friction to get riders from Point A to Point B. People ride bikes to work, to school, to visit friends, for fun, and for exercise. The simple-looking machine is a complex mechanical work of art that has undergone centuries of development, optimization, and testing to make it as safe and enjoyable as possible.

Cycling is a great way to increase your physical fitness and enjoy the outdoors, without having to worry about traffic or parking. It also helps you save on bus and fuel costs, and reduces your carbon footprint. It is a great cardiovascular workout that tones and strengthens your leg and thigh muscles, as well as increasing your endurance.

It improves your mental health too, by reducing stress levels and improving your mood. This is because any mild-to-moderate activity releases natural feel-good endorphins, helping to counteract feelings of stress and depression. It is also a great social activity that can help you meet new people and build up your social network. You can cycle with your friends, family, or even take part in cycling races and competitions to further enlarge your circle of friends.

In addition, cycling is a low-impact form of exercise that can be enjoyed by almost anyone, regardless of age or fitness level. In fact, children can start learning to cycle at a very young age, and it is an excellent way to get them into the habit of regular exercise. Moreover, cycling is a very affordable and convenient mode of transport for families, as it can be used to commute between home and work, and also to run errands.

Bicycles can be modified with a variety of accessories to suit the needs of the rider. For example, pegs can be fastened to one or both of the wheel hubs to either help the rider perform certain tricks, or allow a place for an extra rider to stand or rest. Parents often add rear-mounted child seats or auxiliary saddles fitted to the crossbar to transport children. The wheels of the bicycle can also be equipped with a suspension to absorb shock.

The basic design of the modern bicycle has changed little since its invention, but there are many different types and configurations of components available. The most important factor in making a bicycle stable is the interaction between the rider and the bicycle, rather than any single component. The design and configuration of the individual parts have been optimized through a process of trial and error to achieve this, and are the subject of ongoing research and development.

Whether you choose to ride a road bike, a mountain bike, or an electric bicycle, you will find that the principles of stability remain the same. A key part of this interaction is the gyroscopic effect, which can be described as the bicycle’s tendency to stay upright as you pedal. This effect works in conjunction with other parts of the bicycle’s geometry, including the frame design, crank axle and pedals, seat tube angle, chainring configuration, and other factors.

A board game in which two players place stones (black and white) to mark territory, the earliest records of go date back to Japan in the 14th century. The game has long been an important part of traditional Japanese culture and was introduced to the West in the 19th century, although interest waned until the 1960s, when some Westerners received formal training from East Asian professionals. Since then, the number of active go players has grown rapidly worldwide. The highest rank in go is 9 dan.

The National Oceanic and Atmospheric Administration’s Geostationary Operational Environmental Satellites (GOES) system provides continuous imagery of Earth and real-time data that help NOAA weather forecasters provide accurate and timely warnings about severe storms. NOAA’s GOES fleet is a key component of the nation’s space weather system, providing critical information to electric power networks, satellite and terrestrial communications, the International Space Station astronauts and crew members, high altitude aviators, geophysical explorers, and scientific researchers.

GOES consists of five satellites in a geostationary orbit 22,300 miles above Earth. Each carries an Imager and a Sounder instrument. The Imager detects electromagnetic radiation that is reflected from Earth’s surface and atmosphere, and the Sounder measures vertical atmospheric temperature and moisture profiles.

Both instruments record and transmit telemetry data to a ground station that translates the data into images for display on a map, and the Sounder also records the motion of Earth’s surface and surface water. The GOES-9 satellite, launched in September 2013, has the longest mission to date and will operate for a maximum of ten years.

One of the most useful aspects of GOES imagery is that it can be observed on very short time intervals, such as 10-minute “full disk” images, which allow meteorologists to monitor rapidly developing severe storms and other events, even in observationally limited areas such as over oceans or mountains. These rapid observations are particularly critical in assisting NOAA’s national weather centers and Volcanic Ash Advisory Centers in monitoring aircraft hazards associated with volcanic eruptions.

In addition, GOES-16 and -17 are capable of observing lightning activity over a wide area of the Western Hemisphere on very short time intervals—a capability that significantly enhances the utility of lightning and thunderstorm climatology products (Goodman et al., 2012; Stano et al., 2014). GOES-R will extend this capability to a much wider region over the entire Earth and will also monitor the Sun’s solar environment with its suite of instruments. This will allow a better understanding of how the solar cycle affects the Earth’s weather and climate. The GOES-R instrument suite will include the following: