Solar System & the Earth and basics

The Roman Warm Period was a period of unusually warm weather in Europe and the North Atlantic that ran from approximately 250 BC to AD 400.
The Medieval Warm Period (MWP) or Medieval Climate Anomaly was a time of warm climate in the North Atlantic region lasting from about 900–1300 AD.
The Little Ice Age (LIA), climate interval that occurred from the early 14th century through the mid-19th century, when mountain glaciers expanded at several locations, including the European Alps, New Zealand, Alaska, and the southern Andes, and mean annual temperatures across the Northern Hemisphere declined.

# As per a new study by the Wadia Institute of Himalayan Geology (WIHG), an autonomous institute of the Department of Science & Technology (DST); Global climatic events like the Roman Warm Period, Medieval Climate Anomaly, and the Little Ice Age may have had significant impacts on India’s landscape, vegetation, and socio-economic growth, with abrupt shifts in the Indian Summer Monsoon (ISM) coinciding with these climatic events.

Quasars are extremely remote celestial objects, emitting exceptionally large amounts of energy.
Quasars are believed to produce their energy from supermassive black holes in the center of the galaxies in which the quasars are located. Because quasars are so bright, they drown out the light from all the other stars in the same galaxy.

Sagittarius A* is a bright and very compact astronomical radio source at the Galactic Center of the Milky Way. Based on mass and increasingly precise radius limits, astronomers have concluded that Sagittarius A* is the Milky Way’s central supermassive black hole.
Nobel Prize 2020 (Physics) winners Reinhard Genzel and Andrea Ghez each lead a group of astronomers that, since the early 1990s, has focused on a region called Sagittarius A* at the centre of our galaxy. Their pioneering work has produced the most convincing evidence yet of a supermassive black hole at the centre of the Milky Way.

Statement 1 is correct. ‘Opposition’ is the event when the Sun, Earth and an outer planet are lined up, with the Earth in the middle. Mars opposition event is when Mars is directly on the opposite side of Earth from the Sun. During this opposition, Mars and Earth are closest to each other in their orbits.
Statement 2 is incorrect. Mars Close Approach was Oct. 6, 2020; that is the point in Mars’ orbit when it comes closest to Earth, this time at about 38.6 million miles (62.07 million kilometers) from our planet, the opposition will happen on October 13.
Close Approach is when Mars and Earth come nearest to each other in their orbits around the sun. Close is a relative term. The minimum distance from Earth to Mars is about 33.9 million miles (54.6 million kilometers). However, that doesn’t happen very often.
In 2003, Mars made its closest approach to Earth in nearly 60,000 years! It won’t be that close again until the year 2287.

Statement 1 is incorrect. A gravitational wave is an invisible (yet incredibly fast) ripple in space. Gravitational waves travel at the speed of light (186,000 miles per second). These waves squeeze and stretch anything in their path as they pass by. A gravitational wave is an invisible (yet incredibly fast) ripple in space.
In 2015, scientists detected gravitational waves for the very first time. They used a very sensitive instrument called LIGO (Laser Interferometer Gravitational-Wave Observatory). These first gravitational waves happened when two black holes crashed into one another. The collision happened 1.3 billion years ago.
Statement 2 is incorrect. A black hole is a region of space where matter has collapsed in on itself and the gravitational pull is so strong that nothing, not even light, can escape. Black holes emerge from the explosive demise of certain large stars, but some are truly gargantuan and are billions of times the mass of our Sun.
Black holes are detected from the way they influence their surroundings, they produce observable gravitational waves as they spiral in to each other.
# Scientists from LIGO and Virgo have detected the largest collision between two black holes to date, which appears to have created an “intermediate-mass” black hole.
# LIGO-VIRGO collaboration operates three super-sensitive gravitational wave-detection systems in America and Europe.

The solar cycle is the cycle that the Sun’s magnetic field goes through approximately every 11 years. This means that the Sun’s north and south poles switch places. Then it takes about another 11 years for the Sun’s north and south poles to flip back again.
Statement 1 is incorrect. Recently, scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA), USA announced their predictions about the new solar cycle, called Solar Cycle 25, which they believe has begun.
The Solar Cycle 25 Prediction Panel, an international group of experts co-sponsored by NASA and NOAA, announced that solar minimum occurred in December 2019, marking the start of a new solar cycle. Because our Sun is so variable, it can take months after the fact to declare this event. Scientists use sunspots to track solar cycle progress.
Statement 2 is incorrect. The beginning of a solar cycle is a solar minimum, or when the Sun has the least sunspots. Over time, solar activity and the number of sunspots increase.
The middle of the solar cycle is the solar maximum, or when the Sun has the most sunspots. As the cycle ends, it fades back to the solar minimum and then a new cycle begins.

Statement 1 is correct. Venus has a thick, toxic atmosphere filled with carbon dioxide and it’s perpetually shrouded in thick, yellowish clouds of mostly sulfuric acid that trap heat, causing a runaway greenhouse effect.
It’s the hottest planet in our solar system, even though Mercury is closer to the Sun. Venus has crushing air pressure at its surface – more than 90 times that of Earth.

Statement 2 is incorrect. The former Soviet Union is the only nation to land on the surface of Venus to date, though the spacecraft did not survive long in the harsh environment.
The Soviet Union’s Venera 13 in 1982 survived the intense heat and crushing pressure of Venus’ surface for around two hours and transmitted color images from the surface of Venus.

Both statements are correct.
Water makes up about 71% of the Earth’s surface, while the other 29% consists of continents and islands.
About 96.5% of all the Earth’s water is contained within the oceans as salt water, while the remaining 3.5% is freshwater lakes and frozen water locked up in glaciers and the polar ice caps. Of that fresh water, 69% of it takes the form of ice.

An Isarithmic map is a type of thematic map that represents a continuous field using line and/or region symbols to connect places of similar value.

 It is sometimes called a heat map, although the term heat map should only be used for one type of isarithmic map that represents density.

 In general, these maps are used to help visualize continuous data sets by utilizing color, especially hue and value.

 There are a number of ways to symbolize isarithmic maps; no matter the design method, the phenomenon being represented must be a quantitative continuous field.

 Contour maps, Isotherm maps and Isobar maps are the examples of isarithm maps.

Kandla port city is the nearest to tropic of cancer in India.

The Indian Standard Meridian passes through mostly 5 states which are

Uttar Pradesh, Madhya Pradesh, Chhattisgarh, Odisha and Andhra Pradesh

British India did not adopt the international standard time zones until 1905 when

the meridian passing through Allahabad at 82.5º east (of Greenwich Meridian) longitude

was picked as the central meridian for India, corresponding to a single time zone for the

country at 5 hours and 30 minutes in advance of GMT. This went into force on January 1,

1906. However, Calcutta time was officially maintained as a separate time zone until 1948.

Bombay time was maintained but only informally until about 1955. After independence and

the partition of British India, Pakistan stayed on Indian Standard Time for three years and

adopted Pakistan Standard Time at 5 hours in advance of GMT in 1951.

About 71 per cent of the planetary water is found in the oceans. The

remaining is held as freshwater in glaciers and icecaps, groundwater sources, lakes, soil

moisture, atmosphere, streams and within life.

80* E longitude passes near through Kanpur (UP), Jabalpur (MP), Nellore in

Andhra Pradesh and Chennai in Tamil Nadu.

The Indian Ocean is the world’s third largest ocean and covers 70,560,000

km². Three continents have coastlines on the Indian Ocean; these are Asia, Africa,

and Australia to the north, west, and east respectively. The Indian Ocean meets

the Southern Ocean to the south. The Indian Ocean is home to hundreds of islands. Six

island nations are located in the Indian Ocean, namely Comoros, Madagascar, Maldives,

Mauritius, Seychelles, and Sri Lanka.

An isohyet is also known as isohyetal line, and it is a line on a map which

connects points that have the same amounts of precipitation in a given period or for a particular storm. The method used in estimating average rainfall across a particular area is

known as an isohyetal method.

• Isotherm: a line on a map connecting points having the same temperature at a

given time or on average over a given period.

• Isobar: A line drawn on a weather map connecting points of equal pressure is called

an isobar. The isobars are generated from mean sea level pressure reports and

the pressure values are given in millibars.

Temperature inversion is a reversal of the normal behavior of temperature in

the troposphere, in which a layer of cool air at the surface is overlain by a layer of warmer

air. (Under normal conditions, temperature usually decreases with height).

Ideal Conditions for Temperature Inversion:

• Long nights, so that the outgoing radiation is greater than the incoming radiation.
• Clear skies, which allow unobstructed escape of radiation.
• Calm and stable air, so that there is no vertical mixing at lower levels.

A map is a representation of a selection of real features on the Earth.

 It is designed to record the relationships between features and to allow these relationships to be analyzed.

 A map may be very simple (e.g. a sketch showing the location of plants in your garden) or very complex (e.g. a topographic map of the Australian Alps).

General Maps: These are simple maps showing important physical (natural and man–made) features in an area.

 Their main purpose is to summarize the landscape to aid discovery of locations.

 They are usually easy to read and understand. Most of the early mapping of the Earth falls into this group.

Thematic Maps: These are maps which depict information on a particular topic or theme.

 The detail portrayed on a thematic map may be physical, statistical, measured, or interpreted, and sometimes requires specialist knowledge by the map user.

• Weather, population density and geology maps are examples of thematic maps.

Topographic Maps: Like General Reference Maps, Topographic Maps are a summary of the landscape and show important physical (natural and man-made) features in an area. The primary difference is that they show elevation in detail.

Cadastral Maps: The cadastre of a country is its register of property titles and is usually managed by government agencies.

 The information recorded includes an accurate description of the location of a parcel of land and who owns it.

 It may also record what the land can be used for (e.g. residential or not, national park etc) and may also show the location and shape of buildings.

A datum is a system which allows the location of latitudes and longitudes (and heights) to be identified onto the surface of the Earth – i.e. onto the surface of a ’round’ object.

A projection is a process which uses the latitude and longitude which has already been ‘drawn’ on the surface of the Earth using a datum, to then be ‘drawn’ onto a ‘flat piece of paper’ – called a map.

The highest tides in the world occur in the Bay of Fundy in Nova Scotia, Canada.

 The tidal bulge is 15 – 16 m. Because there are two high tides and two low tides every day (roughly a 24 hour period); then a tide must come in within about a six hour period

• As a rough estimate, the tide rises about 240 cm an hour (1,440 cm divided by 6 hours).

Lucky latitudes are refers to the geographical regions where the practice of domestication of wild plants and animals began to happen for the first time in human history.

 It includes land that lies between the latitudes of 20 and 35 degrees north in the Old World, and 15 degrees south and 20 degrees north in the Americas.

 These regions became more favourable to the rise of civilization when the rise in earth’s temperature ended the last Ice Age around 12,000 years ago

• Consequently, people located in these geographic regions gained a head-start over the rest of the world.

 The term was coined by Ian Morris in his book Why the West Rules — For Now.

Studying debris-laden Himalayan glaciers is important from the point of view of how climate change affects them.

 About 20% of Himalayan glaciers are debris-laden, and their dynamics are very different from the ones without debris cover.

 In glaciers without a debris cover, the rate of melting increases as the elevation decreases.

 However, in glaciers covered with debris, the thick cover partially insulates the glacier from the warm exterior and thereby slows down the melting.

 The thickness of the debris cover, by and large, increases as the glacier flows down.

 This works against the general trend that the lower the elevation, the higher the rate of melting.

 Matters are further complicated because the thickness of the debris cover is not uniform but fluctuates randomly.

Dozens of people will undertake a “funeral march” up a steep Swiss mountainside on September 2019, to mark the disappearance of an Alpine glacier amid growing global alarm over climate change.

 Dressed in black, they will make the solemn two-hour “funeral march” up the side of Pizol mountain in northeastern Switzerland to the foot of the steep and rapidly melting ice formation, situated at an altitude of around 2,700 metres (8,850 feet) near the Liechtenstein and Austrian borders

 The move comes after Iceland made global headlines last month with a large ceremony and the laying of a bronze plaque to commemorate Okjokull, the island’s first glacier lost to climate change.

 The researchers indicated that the Alps’ largest glacier, the mighty Aletsch, could completely disappear over the next eight decades.

In the course of a year, the earth’s revolution round the sun with its axis inclined at 66 ½ to the plane of the ecliptic changes the apparent altitude of the midday sun.

 The sun is vertically overhead at the equator on two days each year. These are usually 21st march and 21st September.

 After the March equinox the sun appears at move north and is vertically overhead at the tropic of cancer on about 21st June.

 By about 22nd December, the sun will be overhead at the tropic of Capricorn.

 The tropics thus mark the limits of the overhead sun, for beyond these, the sun is never overhead at any time of the year.

Stevenson screen: A Stevenson screen (also known as an instrument shelter) is a meteorological screen to shield instruments against precipitation and direct heat radiation from outside sources, while still allowing air to circulate freely around them.

It forms part of a standard weather station.

Beaufort scale: The Beaufort Scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale.

Hygrometer: Hygrometer, instrument used in meteorological science to measure the humidity, or amount of water vapour in the air.

Istanbul, the largest city in Turkey and the fifth-largest city in the world by population, is considered European, yet it occupies two different continents.

 One part of Istanbul lies in Europe and the other part lies in Asia.

 Istanbul’s European part is separated from its Asian part by the Bosphorus strait, a 31-km-long waterway that connects the Black Sea with the Sea of Marmara, and forms a natural boundary between the two continents.

 Two suspension bridges across the Bosphorus—the Bosphorus Bridge and the Fatih Sultan Mehmet Bridge, also called Bosphorus Bridge II—connect the two sides, yet many tourists prefer to visit the European side of Istanbul because of its historical significance.

• The European side is also the city’s commercial center with banks, stores and corporations and two-third of its population.

 The Asian side feels more relaxed, with wide boulevards, residential neighbourhoods and fewer hotels and tourist attractions.