The concept of aberration It has multiple uses and meanings, as the dictionary of the Royal Spanish Academy (RAE) . The word, as officially accepted, may refer to a very serious error associated with the ability to understand ; when operating depraved or perverse , which is far from what is considered as lawful; to the deviation of the normal type that, in certain situations, experiences a morphological or physiological character; or to the apparent deviation of the stars, among others.
The aberration in optical systems (such as mirrors, lenses or prisms) implies a degradation of images that occurs when the light that comes from a certain point of an object does not converge towards a single point once it has been transmitted by system.
Other aberrations linked to the light that can be identified are the spherical aberration (a defect characterized in that the light rays that strike parallel to the optical axis are diverted to a different focus) and the chromatic aberration (the alteration of the image distance with the index of refraction).
Aberration of light
He phenomenon which describes the different position of a star when observed with respect to the real one is called aberration of light. James Bradley, a professor of astronomy at the University of Oxford, discovered this peculiarity in the year 1725, while seeking to establish the distance between a star and our planet. For this, he made two observations, each one at different times of the year, with the aim of achieving a more precise triangulation of the star, thanks to the Earth's orbital movement.
Bradley noticed in amazement that the fixed stars presented a translation Systematic that was linked to the direction of the earth's movement in its orbit and that did not depend on the location of our planet in space, as previously believed. The highest value of variation between the observed position of a star and the true one is 20.47 arc seconds; this is known as aberration constant. If we calculate its trigonometric tangent, we obtain a result very close to the ratio of the Earth's orbital velocity and that of light.
A chromosomal type aberration It constitutes an error that arises during the meiosis of gametes or when the first egg divisions take place, a phenomenon that triggers an anomaly that influences the number or composition of chromosomes. This phenomenon can cause multiple disorders, such as the development of the so-called Down's Syndrome.
The disturbance it can occur in the structure of the chromosome with respect to the linear ordering of genes, and the reasons are several, as well as their characteristics and consequences. We cite some below:
* Deletions: when a fragment of the chromosome is lost, either at one end or along one of its arms, generating an imbalance, appreciable in Prader-Willi syndrome;
* Duplications: causes a living being to contain extra genetic material, since a chromosomal region doubles, as in fragile X syndrome;
* Investments: it consists in the change of orientation of a segment of the chromosome, and usually does not cause disorders considerable. Can be pericentric, if the centromere is included in the inverted part, or paracentric, when it is not so;
* Ring chromosome: This alteration is uncommon and involves the fusion of both arms of a chromosome. Its development on the X chromosome is one of the causes of Turner syndrome;
* Translocations: describes the transfer of a portion of one chromosome to another, which does not imply loss or gain of information genetics.