A Google Doodle is a special, temporary alteration of the logo on Google's homepages intended to commemorate holidays, events, achievements, and notable historical figures. The first Google Doodle honored the 1998 edition of the long-running annual Burning Man event in Black Rock City, Nevada, and was designed by co-founders Larry Page and Sergey Brin to notify users of their absence in case the servers crashed. Subsequent Google Doodles were designed by an outside contractor until 2001, when Page and Brin asked public relations officer Dennis Hwang to design a logo for Bastille Day. Since then, a team of employees called "Doodlers" have organised and published the Doodles.
Initially, Doodles were neither animated nor hyperlinked—they were simply images with hover text describing the subject or expressing a holiday greeting. Doodles increased in both frequency and complexity by the beginning of the 2010s. In January 2010 the first animated Doodle honored Sir Isaac Newton. The first interactive Doodle appeared shortly thereafter celebrating Pac-Man, and hyperlinks also began to be added to Doodles, usually linking to a search results page for the subject of the Doodle. By 2014, Google had published over 2,000 regional and international Doodles throughout its homepages, often featuring guest artists, musicians, and personalities. By 2019, the "Doodlers" team has created over 4,000 doodles for Google's homepages around the world.
In addition to celebrating many well-known events and holidays, Google Doodles celebrate artists and scientists on their birthdays, including Mary Somerville, Andy Warhol, Albert Einstein, Leonardo da Vinci, Rabindranath Tagore, Louis Braille, Ella Fitzgerald, Percival Lowell, Edvard Munch, Nikola Tesla, Béla Bartók, René Magritte, Norman Hetherington, John Lennon, Michael Jackson, Vladimir Dakhno, Robert Moog, Akira Kurosawa, Satyajit Ray, H. G. Wells, Freddie Mercury, Samuel Morse, Hans Christian Orsted, Mahatma Gandhi, Dennis Gabor, Édith Piaf, Constantin Brâncuși, Antonio Vivaldi, Abdel Halim Hafez, Jules Verne, Leonhard Euler, Lucille Ball, Hedy Lamarr, and James Welch, among over 9,000 others. The featuring of Lowell's logo design coincided with the launch of another Google product, Google Maps. Google Doodles are also used to depict major events at Google, such as the company's own anniversary. The celebration of historic events is another common topic of Google Doodles including a Lego brick design in celebration of the interlocking Lego block's 50th anniversary. Some Google Doodles are limited to Google's country-specific home pages while others appear globally
Dating back to the 14th century in Nuremberg, Germany, Elisenlebkuchen have stood the test of time as one of Germany’s most popular and beloved of all Christmas treats!
Lebkuchen go all the way back to 14th century Germany where they were created by Catholic monks. Prepared in monastery bakeries, Lebkuchen included honey, a variety of spices and nuts. These ingredients not only had symbolic religious meaning but were highly prized for their healing properties. Those clever monks not only created an exceptionally delicious sweet treat, they found an additional use for their communion wafers: They increased the diameter size and used them as the base for the sticky gingerbread dough – a perfect solution.
A quintessential sweet treat throughout all of Germany during the Christmas season, Lebkuchen is one of the most popular and beloved of all German holiday confections. There are a variety of German Lebkuchen, each distinguished by slight alterations in ingredients and most especially the amount of nuts used. But the most highly prized of all are the Nürnberger Elisenlebkuchen. The title is a regionally protected one and only Lebkuchen produced in Nürnberg can be sold as such. The distinguishing characteristic of the Elisenlebkuchen is that they use no flour and have a very high ratio of nuts, specifically a combination of almonds and hazelnuts.
120g brown sugar
1 tsp cinnamon
1 tsp ginger powder
1/2 tsp ground cloves (or allspice)
1 vanilla pod, seeds
2 whole eggs
2 tsp cocoa powder
440g plain flour
1 tsp baking powder
In a small pot gently heat the butter, sugar and honey and stir regularly until the sugar has completely dissolved.
While this is happening, mix together all the other ingredients in a big bowl.
Then add the liquid honey/butter/sugar mix to this (you'll either need a spoon and strong arms, or a kitchen aid machine with a kneading hook attachment).
Now leave the dough to rest/cool down for an hour at room temperature.
Pre-heat your oven to 180 degrees. (160 if fan-assisted)
After an hour, roll out the dough to about 1cm thickness and cut out gingerbread men or any other shapes you prefer (if the dough is too sticky, place it in the fridge for a few minutes to firm-up, or knead it with your hands and add a bit more flour).
Place the cookies on a tray lined with baking paper, and bake for approx. 10min. (they will still be slightly soft to the touch; this is what you are aiming for!)
Once cool, feel free to frost them with icing, sugar pearls, or any other kinds of sweet decoration!
An automotive navigation system is part of the automobile controls or a third party add-on used to find direction in an automobile. It typically uses a satellite navigation device to get its position data which is then correlated to a position on a road. When directions are needed routing can be calculated. On the fly traffic information can be used to adjust the route.
Dead reckoning using distance data from sensors attached to the drivetrain, a gyroscope and an accelerometer can be used for greater reliability, as GPS signal loss and/or multipath can occur due to urban canyons or tunnels.
Mathematically, automotive navigation is based on the shortest path problem, within graph theory, which examines how to identify the path that best meets some criteria (shortest, cheapest, fastest, etc.) between two points in a large network.
Automotive navigation systems are a crucial for the development of self-driving cars.
he road database is a vector map. Street names or numbers and house numbers, as well as points of interest (waypoints), are encoded as geographic coordinates. This enables users to find a desired destination by street address or as geographic coordinates.
Map database formats are almost uniformly proprietary, with no industry standards for satellite navigation maps, although some companies are trying to address this with SDAL and Navigation Data Standard (NDS). Map data vendors such as Tele Atlas and Navteq create the base map in a GDF (Geographic Data Files) format, but each electronics manufacturer compiles it in an optimized, usually proprietary manner. GDF is not a CD standard for car navigation systems. GDF is used and converted onto the CD-ROM in the internal format of the navigation system.
DAL is a proprietary map format developed by Navteq, which was released royalty free in the hope that it would become an industry standard for digital navigation maps, has not been very widely adopted by the industry. Vendors who used this format include:
Navigation Data Standard (NDS)
The Navigation Data Standard (NDS) initiative, is an industry grouping of car manufacturers, navigation system suppliers and map data suppliers whose objective is the standardization of the data format used in car navigation systems, as well as allow a map update capability. The NDS effort began in 2004 and became a registered association in 2009. Standardization would improve interoperability, specifically by allowing the same navigation maps to be used in navigation systems from 20 manufacturers. Companies involved include BMW, Volkswagen, Daimler, Renault, ADIT, Aisin AW, Alpine Electronics, Navigon, Navis-AMS, Bosch, DENSO, Mitsubishi, Harman International Industries, Panasonic, Preh Car Connect formerly TechniSat, PTV, Continental AG, Clarion, Navteq, Navinfo, TomTom and Zenrin.
The road database may be stored in solid state read-only memory (ROM), optical media (CD or DVD), solid state flash memory, magnetic media (hard disk), or a combination. A common scheme is to have a base map permanently stored in ROM that can be augmented with detailed information for a region the user is interested in. A ROM is always programmed at the factory; the other media may be preprogrammed, downloaded from a CD or DVD via a computer or wireless connection (bluetooth, Wi-Fi), or directly used utilizing a card reader.
Some navigation device makers provide free map updates for their customers. These updates are often obtained from the vendor's website, which is accessed by connecting the navigation device to a PC.
Main article: Integration of traffic data with navigation systems
Some systems can receive and display information on traffic congestion using either TMC, RDS, or by GPRS/3G data transmission via mobile phones.
In practice, Google has updated Google Maps for Android and iOS to alert users when a faster route becomes available in 2014. This change helps integrate real-time data with information about the more distant parts of a route.
Integration and other functions
The color LCD screens on some automotive navigation systems can also be used to display television broadcasts or DVD movies.
A few systems integrate (or communicate) with mobile phones for hands-free talking and SMS messaging (i.e., using Bluetooth or Wi-Fi).
Automotive navigation systems can include personal information management for meetings, which can be combined with a traffic and public transport information system.
Original factory equipment
Many vehicle manufacturers offer a GPS navigation device as an option in their vehicles. Customers whose vehicles did not ship with GPS can therefore purchase and retrofit the original factory-supplied GPS unit. In some cases this can be a straightforward "plug-and-play" installation if the required wiring harness is already present in the vehicle. However, with some manufacturers, new wiring is required, making the installation more complex.
The primary benefit of this approach is an integrated and factory-standard installation. Many original systems also contain a gyrocompass and/or an accelerometer and may accept input from the vehicle's speed sensors and reverse gear engagement signal output, thereby allowing them to navigate via dead reckoning when a GPS signal is temporarily unavailable. However, the costs can be considerably higher than other options.
Establishing points of interest in real-time and transmitting them via GSM cellular telephone networks using the Short Message Service (SMS) is referred to as Gps2sms. Some vehicles and vessels are equipped with hardware that is able to automatically send an SMS text message when a particular event happens, such as theft, anchor drift or breakdown. The receiving party (e.g., a tow truck) can store the waypoint in a computer system, draw a map indicating the location, or see it in an automotive navigation system.
Satire is a genre of literature and performing arts, usually fiction and less frequently in non-fiction, in which vices, follies, abuses and shortcomings are held up to ridicule, ideally with the intent of shaming individuals, corporations, government, or society itself into improvement. Although satire is usually meant to be humorous, its greater purpose is often constructive social criticism, using wit to draw attention to both particular and wider issues in society.
A feature of satire is strong irony or sarcasm —"in satire, irony is militant", according to literary critic Northrup Frye— but parody, burlesque, exaggeration, juxtaposition, comparison, analogy, and double entendre are all frequently used in satirical speech and writing. This "militant" irony or sarcasm often professes to approve of (or at least accept as natural) the very things the satirist wishes to question.
Satire is found in many artistic forms of expression, including internet memes, literature, plays, commentary, music, film and television shows, and media such as lyrics. The word satire comes from the Latin word satur and the subsequent phrase lanx satura. Satur meant "full" but the juxtaposition with lanx shifted the meaning to "miscellany or medley": the expression lanx satura literally means "a full dish of various kinds of fruits"
The word satire derives from satura, and its origin was not influenced by the Greek mythological figure of the satyr.
Laughter is not an essential component of satire; in fact there are types of satire that are not meant to be "funny" at all. Conversely, not all humour, even on such topics as politics, religion or art is necessarily "satirical", even when it uses the satirical tools of irony, parody, and burlesque.
Even light-hearted satire has a serious "after-taste": the organizers of the Ig Nobel Prize describe this as "first make people laugh, and then make them think"
The rules of satire are such that it must do more than make you laugh. No matter how amusing it is, it doesn't count unless you find yourself wincing a little even as you chuckle. Historically, satire has satisfied the popular need to debunk and ridicule the leading figures in politics, economy, religion and other prominent realms of power. For its nature and social role, satire has enjoyed in many societies a special freedom license to mock prominent individuals and institutions. The satiric impulse, and its ritualized expressions, carry out the function of resolving social tension. Institutions like the ritual clowns, by giving expression to the antisocial tendencies, represent a safety valve which re-establishes equilibrium and health in the collective imaginary, which are jeopardized by the repressive aspects of society. Satire confronts public discourse and the collective imaginary, playing as a public opinion counterweight to power (be it political, economic, religious, symbolic, or otherwise), by challenging leaders and authorities. For instance, it forces administrations to clarify, amend or establish their policies. Satire's job is to expose problems and contradictions, and it's not obligated to solve them. Karl Kraus set in the history of satire a prominent example of a satirist role as confronting public discourse.
The Jataka tales are a voluminous body of literature native to India concerning the previous births of Gautama Buddha in both human and animal form. The future Buddha may appear as a king, an outcast, a god, an elephant—but, in whatever form, he exhibits some virtue that the tale thereby inculcates.
n Theravada Buddhism, the Jātakas are a textual division of the Pāli Canon, included in the Khuddaka Nikaya of the Sutta Pitaka. The term Jātaka may also refer to a traditional commentary on this book. The tales are dated between 300 BC and 400 AD
History Mahāsāṃghika Caitika sects from the Āndhra region took the Jātakas as canonical literature and are known to have rejected some of the Theravāda Jātakas which dated past the time of King Ashoka
he Caitikas claimed that their own Jātakas represented the original collection before the Buddhist tradition split into various lineages.
Although many Jātakas were written from an early period, which describe previous lives of the Buddha, very little biographical material about Gautama's own life has been recorded.
The Jātaka-Mālā of Arya Śura in Sanskrit gives 34 Jātaka stories. At the Ajanta Caves, Jātaka scenes are inscribed with quotes from Arya Shura, with script datable to the sixth century. It had already been translated into Chinese in 434 CE. Borobudur contains depictions of all 34 Jatakas from Jataka Mala.
A digital twin is a digital replica of a living or non-living physical entity. Digital twin refers to a digital replica of potential and actual physical assets (physical twin), processes, people, places, systems and devices that can be used for various purposes
In Karnataka Sate of South India, the udupi and mangalore region is known for its healthy and tasty delicacy it holds in its cuisine. Most of the recipe belongs to the breakfast and snacks but it does have lot of traditional recipes too. one such unique and traditional sweet recipe is halbai recipe or rice halbai halwa made for occasions and festival.halbai sweet hails from the world famous udupi or south canara cuisine. and it is very popular dessert recipe across the coastal belt. having said that, it would be unfair to call it as a karnataka cuisine recipe. as many non coastal kannadiga’s may not be aware of this recipe. as matter of fact, you may have to develop a taste for this sweet. if you are totally new to this recipe, you may find it weird. anyway, some tips, suggestions and variations to this classic rice based halbai recipe. firstly, i have used normal day to day use sona masuri rice to make the rice batter. and i would heavily recommend to use the same and avoid especially basmati rice as it does not yield smooth rice batter. secondly, the recipe uses jaggery for sweetness and using jaggery gives a nice texture and colour to the sweet. however, if you do not have access to it, you can use brown sugar as alternative. lastly, you have to continuously stir and mix the batter and jaggery mixture on a low flame. you may find it tiring, but unfortunately there isn’t any shortcut for this step.
▢ 1 cup rice
▢ 1 cup coconut
▢ 3 cup water
▢ 1 cup jaggery
▢ ¼ tsp salt
▢ 2 tbsp ghee / clarified butter
▢ ¼ tsp cardamom powder
firstly, in a large bowl soak 1 cup rice for 2 hours.
drain off the water and transfer to the blender.
add 1 cup coconut and ¼ cup water.
blend to smooth paste, keep aside.
in a large kadai take 1 cup jaggery and add 2¾ cup water.
stir well until the jaggery dissolves completely.
add in prepared rice coconut paste, ¼ tsp salt and stir well.
stir until the mixture is well combined without forming lumps.
further, add 2 tbsp ghee and mix well.
the mixture will start to turn glossy and separates the pan after 15 minutes.
level up spreading uniformly. rest for 30 minutes or until it sets completely.
after 30 minutes, slowly unmould the halbai.
finally, garnish with cashew and enjoy halbai or rice halwa with ghee during nagarpanchami festival.
The American pika (Ochotona princeps) is traditionally thought of as a canary in the coal mine when it comes to America's rising temperatures.
Making their homes high up in the cooler mountain regions of western North America, these adorable critters can overheat in high temperatures – making them incredibly sensitive to climate change.
A new literature review by conservationist Andrew T. Smith says otherwise – that the pika is doing remarkably well considering the circumstances.
"These results show that pikas are able to tolerate a broader set of habitat conditions than previously understood," Smith explains.
American pikas are small, territorial, rabbit-like creatures, that spend their days eating grasses and thistles, storing food for winter, squeaking at predators, and singing songs to potential mates.
They live in the mountains of Western North America – from British Columbia and Alberta in Canada all the way to New Mexico and California.
They make their homes in the mountains' talus fields – a landscape of broken stones and boulders, where they nest nest beneath rocks that keep them cool in hot conditions, and protect them from predators such as eagles, hawks and foxes.
To maintain their climate-controlled nests, scientists think they might slowly migrate further up the mountain to cooler conditions as the climate heats up year on year, but there's only so much mountain to climb before you reach a dead end.
They can't just move mountains when the temperature gets too hot – they're trapped on these sky islands.Smith did note that there are areas where American pikas aren't doing so well – low-elevations that are also isolated at the edges of their range. He thinks this is at least partially due to dispersal, or the spread of the species.
In small, isolated habitat patches there are less resources – including rock shelters – available for young pikas searching for their own nests, especially in the hotter low-elevation areas. The researchers have seen loss of local pika populations in these circumstances.
"Due to the relatively poor ability of pikas to disperse between areas, those habitats are not likely to be recolonised, particularly in light of our warming climate," Smith said in a press release.
"In spite of the general health of pikas across their range, these losses represent a one-way street, leading to a gradual loss of some pika populations."
However, Smith's review highlights the importance of understanding how a species is fairing across its entire range before drawing conclusions.
This obviously doesn't mean that climate change isn't a huge problem – especially for alpine species stuck on sky islands – and one we need to be tackling right now (or yesterday). "Much of the narrative regarding pikas and climate change has been based on studies from a restricted and marginal part of their geographic range," he writes in the paper.
"But because responses of pikas to their environment can vary greatly across their broad geographic range, care should be taken when generalizing from one region to another."
He points to a large range-wide survey back in 2018 done by his team where 3,250 records of occupied (or extant), recently empty (extirpated) or long empty (old-sign) pika sites across 40 mountain ranges were compiled and analysed.
"The large number of pika extant, extirpated, and old-sign, sites across the Great Basin documented by Millar et al., allowed a robust evaluation of how climatic features may have affected pika occupancy," he writes in the paper.
"While there were differences in climate values across six subregions of the Great Basin, for all extant sites the model expanded the range of both temperature and precipitation values compared with most other regions across the range of the species."
"In spite of the general health of pikas across their range, these losses represent a one-way street, leading to a gradual loss of some pika populations."
However, Smith's review highlights the importance of understanding how a species is fairing across its entire range before drawing conclusions.
This obviously doesn't mean that climate change isn't a huge problem – especially for alpine species stuck on sky islands – and one we need to be tackling right now (or yesterday).
But it's nice to know that the tiny American pika might stand more of chance than we thought.
Adai is an Indian pancake popularly made in Tamil Nadu, especially in Tanjavur district, India and is almost similar to dosa. According to Food Blogger Nithya Ravi, "The dish was named Adai because, in olden days, it was made in a bronze vessel with coconut oil.
High in fiber, diabetic and heart friendly. Being an excellent source of folic acid, pregnant women must include toor dal in their daily diet. Being an excellent source of fibre it helps in preventing and relieving gastric problems like constipation.
1 cup Raw rice
1 cup Idli rice/ parboiled rice
1/2 cup Chana dal/ Kadalai paruppu
1/4 cup Toor dal/ thuvaram paruppu
1/8 cup Urad dal/ uluntham paruppu
1/8 cup Moong dal/ paasi paruppu -
1 cup Small onions/shallots chopped
4 tbsp Coriander leaves chopped optional
2 sprigs curry leaves
1/4 tsp Asafoetida
15 Red chillies
Salt to taste
Soak rice and dal separately for 3 hrs minimum. First grind the red chillies with salt, asafoetida and then add rice.
Grind it to a coarse paste (like rava). Add dal. Use the pulse,inch or juice option to grind this dals coarsely. Make sure to wipe the sides and lids for even grinding.
This should be more coarse in texture as shown in the picture. Mix both the ground items well and set aside. You can keep upto 3-4 hours, or even make immediately. But standing time yields better result.
Just before making adai, add the onions, coriander, curry leaves and mix well. The batter should be thicker than our idly dosa batter. So adjust water as needed.
Heat the tawa and spread little oil and spread one laddle full of batter as thick adais,make a small hole in the middle and again pour little oil around. Let it get cooked for sometime.Turn over the adai and cook the other side too till golden brown. (you can cook covered with a lid, before flipping )
Hydrogen peroxide (formula H2O2) is a chemical compound that's a combination of hydrogen and water. The clear liquid acts as a mild antiseptic and comes in various potencies depending on its purpose: 3 percent (household use), 6 to 10 percent (hair bleaching), 35 percent (food-grade) and 90 percent (industrial). Most stores carry the 3 percent solution, packaged in a signature brown bottle.
For years, medical professionals recommended using hydrogen peroxide to treat minor scrapes and cuts. That's because when it's placed on the skin, it foams, which indicates it's killing bacteria. Today, doctors know hydrogen peroxide also kills healthy cells, so many no longer recommend its use for that purpose. It also can be harmful if it gets in your eyes, covers a large area of your skin or is ingested, especially the food-grade hydrogen peroxide.
But no worries. Hydrogen peroxide has many other helpful applications, some of which might be new to you. Here are nine. (The hydrogen peroxide referred to in these examples is the 3 percent version, unless noted otherwise.)
Hydrogen peroxide is a mild antiseptic used on the skin to prevent infection of minor cuts, scrapes, and burns. It may also be used as a mouth rinse to help remove mucus or to relieve minor mouth irritation (e.g., due to canker/cold sores, gingivitis).
1. Remove Pit Stains
Let's face it, brownish-yellow armpit stains are embarrassing. And aggravating, especially if they develop on a fairly new garment. Erase them by creating a solution of one part dishwashing liquid and two parts hydrogen peroxide, then applying it to the stain for about an hour. Wash in cold water, then dry and wear. Note: A tough stain may also require scrubbing with baking soda.
2. Grow Mushrooms
It's crazy, but true. Hydrogen peroxide — the 35 percent version — helps combat mold infections that can ruin 'shrooms. Apply a few drops to fruiting chambers (where mushrooms grow) to instantly add oxygen.
3. Clean the Dishwasher
Use hydrogen peroxide to clean out your dishwasher. You can spray hydrogen peroxide directly into the appliance, let sit a bit, then wipe out. Or you can create a cleaning "bomb" with hydrogen peroxide, baking soda and an essential oil. Mix them and use an ice cream scoop to scoop out round balls. Let them dry overnight. To use, place the bomb at the bottom of the dishwasher. Then mix white vinegar and liquid dish-washing detergent in a glass or ceramic bowl and place in the top of the dishwasher. When you run a cycle with the bomb (along with vinegar and detergent), the peroxide will whiten and clean the appliance while the baking soda scrubs it and the oil provides a fresh scent.
4. Whiten Almost Anything, From Fingernails to Grout
Hydrogen peroxide is great at whitening and brightening many items, such as stained tiles, dirty grout and even fingernails. For the latter, combine one part hydrogen peroxide with two parts baking soda and rub the paste on your nails. Let sit for two or three minutes, then rinse away. Voilà! Gorgeous, white nails. For whitening grout, either pour the hydrogen peroxide straight on to the tile or make a paste with baking soda and scrub away.
6. Boost Your Laundry
No need to buy those expensive commercial laundry products that have the words "oxy" in them and promise to whiten your clothes. Simply add a cup of hydrogen peroxide to your washing machine when doing a load of whites. The hydrogen peroxide will also deodorize clothes and remove stains. You can pour it directly on stains but do a color-fast test first if you're applying to darker clothes.
7. Kill Mold and Mildew
As we noted earlier, hydrogen peroxide kills bacteria, but it also dispatches fungi such as mold and mildew. So grab a spray bottle of hydrogen and spray your bathroom fixtures, floors, walls, humidifier, dehumidifier, even your shower curtain. That fizzy sound will tell you it's working.
8. Grow Your Garden
Gardeners know one of the best substances for their plants is hydrogen peroxide. The all-purpose liquid can help with pest control, prevent infection on damaged trees, kill foliage fungus and combat root rot, as well as improve plant growth. That extra oxygen causes the roots to absorb more nutrients. For pest control or growth, add one teaspoon to one cup of water in a spray bottle and mist the plant. To combat root rot or fungal infections, use one tablespoon per cup of water.
9. Keep Food Fresher
Spraying salad greens with a little H2O2, then returning them to the fridge, will thwart sogginess for several days. Fruits and veggies also can be spritzed or bathed in a hydrogen peroxide solution to keep them fresher longer. Just be sure to rinse them thoroughly before eating.
Editor's note: The regular strength hydrogen peroxide (3-5 percent) is OK to ingest, but higher strengths (10 percent or more) can be toxic if swallowed.
A black hole is a place in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.
Because no light can get out, people can't see black holes. They are invisible. Space telescopes with special tools can help find black holes. The special tools can see how stars that are very close to black holes act differently than other stars.
How Big Are Black Holes?
Black holes can be big or small. Scientists think the smallest black holes are as small as just one atom. These black holes are very tiny but have the mass of a large mountain. Mass is the amount of matter, or "stuff," in an object.
Another kind of black hole is called "stellar." Its mass can be up to 20 times more than the mass of the sun. There may be many, many stellar mass black holes in Earth's galaxy. Earth's galaxy is called the Milky Way.
The largest black holes are called "supermassive." These black holes have masses that are more than 1 million suns together. Scientists have found proof that every large galaxy contains a supermassive black hole at its center. The supermassive black hole at the center of the Milky Way galaxy is called Sagittarius A. It has a mass equal to about 4 million suns and would fit inside a very large ball that could hold a few million Earths.
How Do Black Holes Form?
Scientists think the smallest black holes formed when the universe began.
Stellar black holes are made when the center of a very big star falls in upon itself, or collapses. When this happens, it causes a supernova. A supernova is an exploding star that blasts part of the star into space.
Scientists think supermassive black holes were made at the same time as the galaxy they are in.
If Black Holes Are "Black," How Do Scientists Know They Are There?
A black hole can not be seen because strong gravity pulls all of the light into the middle of the black hole. But scientists can see how the strong gravity affects the stars and gas around the black hole. Scientists can study stars to find out if they are flying around, or orbiting, a black hole.
When a black hole and a star are close together, high-energy light is made. This kind of light can not be seen with human eyes. Scientists use satellites and telescopes in space to see the high-energy light.
Could a Black Hole Destroy Earth?
Black holes do not go around in space eating stars, moons and planets. Earth will not fall into a black hole because no black hole is close enough to the solar system for Earth to do that.
Even if a black hole the same mass as the sun were to take the place of the sun, Earth still would not fall in. The black hole would have the same gravity as the sun. Earth and the other planets would orbit the black hole as they orbit the sun now.
The sun will never turn into a black hole. The sun is not a big enough star to make a black hole.
How Is NASA Studying Black Holes?
NASA is using satellites and telescopes that are traveling in space to learn more about black holes. These spacecraft help scientists answer questions about the universe.