The inability to track stars even with big telescopes in the early days emphasized the need for a steer able mount. The way in which a telescope is mounted should take into account the earth’s rotation. One axis of the telescope mount can be placed horizontally, while the other axis remains vertical . A telescope mount with one axis parallel to the earth’s rotational axis is called equatorial mount. In this mode, one of the axes of the telescope is aligned to the earth’s axis of rotation.
It is the polar axis which points to the celestial pole, the point around which the stars appear to turn . Those in the northern hemispheres aim the polar axis towards Polaris, the northern pole star, while those in the southern hemisphere target the faint Sigma Octantis. When the polar axis is rotated, the telescope moves in the same east-to-west directions as do the stars. Due to the rotation of the earth, everything in the sky apparently moves from east to west. In 12 hours, a telescope can cover 180, which works out to 15 degrees per hours or 15 seconds of arc per second
The other type of mount is called alt-azimuth. As the earth rotates, the target will also move. An observer must therefore keep on rotating the telescope in both directions – left to right or up and down (to change the degree of latitude above or below the celestial equator, called the declination axis) every few seconds. it is possible nowadays to use computers to do precise tracking nowadays . The optical telescope at handle, for instance, has an alt-azimuth mount.
Role of Innovations
Generally, five capabilities are associated with an astronomer:
- Access to a wide range of different wavelength (E.g. gamma rays, x-rays, visible, infrared and radio). This capability is limited by the spectral transmission of optics. (E.g. Glass cuts off ultraviolet and far- infrared)
- Angular resolution : The ability to distinguish sources separated by small angles. (This is limited by what is known as optical diffraction )
- The ability to sense an event in the shortest possible time (For example, a stop watch can show time for 100th of a second , whereas it is possible measure time in other devices in micro or nano seconds)
- Spectral resolution (The ability to distinguish and measure narrow spectral lines);
- Sensitivity, which stands for the ability of an instruments to sense weak signals or distinguish small differences in the intensity of two signals that appear equally bright. The ability to image “bright” and “faint” sources can be in the same system.
Today, research telescopes have cameras and instruments rather than eyes pieces. The capability of astronomers depends to a larger extent on the sophisticated instruments available to them. Innovations in electronics, photonics and computers have resulted in the discovery of new phenomena. The internet enables astronomers to be away from the telescopes (rather than spend right after night in cold places!) and analyses the data later at a more comfortable time and location.
Increase in the angular resolution has led to the discover of quasars, celestial X- ray stars and infrared waves from celestial sources and universal background microwave radiation. Improved time resolution has enabled astronomers to catch transient phenomenon that remains only for short duration such as a pulsar’s pulses, flare stars, gamma rays bursts, black hole accretion disks and supernova remnants. Enhanced spectral resolution has led to the discovery of X-ray galaxies, masers and most recently explained.
Citizen Science Projects
Many new projects have been able to harness to power of the common citizenry by connecting them through the Internet to programs used to analyze data collected from stars. The Zoo Universe project is one such portal which is open to all global citizens across the globe.