When did cell phones come out? The first cell phone in the world was launched in How do prepaid phones work? Prepaid phones are able to provide the same service as phones under contract. Signing up is very convenient and prepaid phones can be found at most retailers. What are the most common everyday devices used today? The most common everyday devices used today are tablets, routers, kindles, wireless mice, and iPhones. Wireless charging pads, desktop computers, laptops, AirPods, smart watches, USB chargers, and wearable technology are also popular everyday devices.
Other common everyday devices include smart TVs, streaming media players, consoles, and VR kits are common everyday devices used today. What is an accelerometer used for in mobile devices? Accelerometers are used in mobile devices to detect changes in orientation, help tell the phone which way is up and down, and tell the screen to rotate.
They are one of the most used features in the smartphone experience and are often taken by granted by people who do now know how the gadget works. What is an iOS device? An iOS device is an electronic device that runs the platform iOS. The iOS platform is the second most popular operating system after Android. Where is the Samsung headquarters? Samsung headquarters are located on the 40th floor of the Samsung Electronics Building.
Samsung headquarters are sometimes referred to as Samsung Digital City and although it is not a city, it is a campus where designs are developed and tested. When was Samsung founded? Samsung was originally founded as a grocery trading store on March 1, Samsung was founded by Lee Byung-Chull and as the years passed Samsung expanded into exporting more materials. Samsung first entered the electronics industry in starting with various electronic divisions and one of their first products was a black and white television.
What products are Samsung popular for today? Samsung has become a global leader in the consumer electronics industry and is mostly known for its smartphones as well as its LCD televisions that have impacted the global market. Samsung is also known for producing semiconductors. Display Size:. Related Collections Samsung Galaxy Smartphones. Phones Cell Phones. Devices Gadgets. Related Tags Work. Text by. Right Click and 'Save As' to Download.
DWG - Imperial Feet. DWG - Metric Meters. Astronomers theorize that this extra mass is dark matter. This matter is not visible, emits no electromagnetic radiation, and has so far eluded detection. There are some alternative theories to dark matter being investigated. These theories propose that there is no extra matter, but that our understanding of gravity is incomplete or inadequate on large scales, and the motion of the stars within our galaxy can be explained this way.
So far none of the alternative theories have been able to explain the observations as cleanly as dark matter and dark matter is the more widely accepted theory. The galactic coordinate system is a way of describing where an object is in the Milky Way Galaxy, relative to the Sun.
This coordinate system doesn't give information about the distance to an object, so many objects may have the same galactic coordinates by being along the same line of sight, but be at different distances from us. The Milky Way Galaxy's disk rotates, with all of the stars and dust in the disk traveling at a fairly uniform speed.
Because of this, stars inside the Sun's orbit complete trips around the bulge more quickly than we do. Stars outside the Sun's orbit complete the journey more slowly. Our galaxy is not like a rotating CD or DVD, where different points on the CD travel at different speeds, but always complete a rotation in the same amount of time.
In our galaxy, stars in the disk all travel at nearly the same speed, so stars closer to the edge will take longer to orbit the galaxy since they have farther to travel. The spiral arms in our galaxy may be density waves, similar to the ripples that form when a stone is dropped into a pool of water.
The spiral arms are areas of greater density of gas, dust and stars, and are the regions where star formation happens. The Milky Way Galaxy is the second largest member of a cluster of over 30 galaxies called the Local Group. The largest member of the local group is the Andromeda Galaxy, and the 3rd largest is the Triangulum galaxy.
Most of the other galaxies in the Local Group are much smaller dwarf spheroidal and dwarf elliptical galaxies. Our Local Group is a member of the Virgo Supercluster, which contains over galaxies and clusters, and is over million light years across. Generally superclusters are not bound to each other gravitationally and are moving away from each other due to the expansion of the universe.
In the s, astronomers began to suspect that the Milky Way is a disk of stars that completely encircles us. However, for a long time astronomers believed that our sun was at the center of the Galaxy. The most luminous Cepheids can be used to estimate distances to objects as far as 12,, light years away.
There are complications in using the period-luminosity relationship. First, the relationship itself depends on the chemical composition of the star. Secondly, the absorption of certain wavelengths of light by the interstellar medium can affect the apparent brightness of the star and therefore must be accounted for.
Even with these and other complications, Cepheid Variables provide an excellent way to measure the relative distances. To convert to absolute distances, we ideally need to measure the distance to a nearby Cepheid with another, more direct, method.
There is much debate at present in this area, in particular regarding the Hipparcos measurements of distances to nearby Cepheids. See the Nearest Stars page for more information on Hipparcos measurements. Interestingly, the size of our own Galaxy was debated for a long while.
It was not until early in the 20th century that Harlow Shapley used observations of RR Lyrae variable stars to estimate our Galaxy's size. RR Lyrae stars are similar to Cepheid Variables. They have relatively short periods, typically of about a day or less, and all RR Lyrae stars have approximately the same luminosity.
Typically, RR Lyrae stars are less luminous than Cepheids, but they are much more common. Globular clusters of stars - swarms of old stars tightly bound together by gravity and orbiting at the outskirts of galaxies, contain many variable stars, including RR Lyraes.
Shapley was able use these to find the distance to the globular clusters that surround our Galaxy. Not only were the globular clusters great distances away, but the Sun did not lie at the center of their distribution, which placed the Sun far from the center of the Galaxy. Shapley's first estimate of the radius of the Milky Way was off by a factor of 2, but he made an important first step in understanding the nature of our Galaxy.
Several more modern methods have been used to map our Galaxy more accurately. The neutral hydrogen gas in our Galaxy emits light at a wavelength of 21 cm; while this light is invisible to our eyes, it is observable to radio telescopes. Other molecules like carbon monoxide also emit radio waves. This is very helpful for mapping the disk portion of our Galaxy.
Distance is a useful tool on the galactic scale.
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