Motion of the Stars

The daily motion of the Sun across the sky is familiar to even the most casual observer. This daily trek is not the Sun moving as early astronomers thought, but the result of the Earth's rotation. The Earth's rotation also causes the stars to do the same, scribing out a large circle as the Earth completes one rotation. The size of the circular path a star follows depends on where it is in the sky. Stars near the celestial equator form the largest circles rising in the east and setting in the west. Moving toward the north celestial pole, the point around which the stars in the northern hemisphere appear to rotate, these circles become smaller. Stars in the mid-celestial latitudes rise in the northeast and set in the northwest. Stars at high celestial latitudes are always above the horizon, and are said to be circumpolar because they never rise and never set. You will never see the stars complete one circle because the sunlight during the day washes out the starlight. However, part of this circular motion of stars in this region of the sky can be seen by setting up a camera on a tripod and opening the shutter for a couple hours. The processed film will reveal semicircles that revolve around the pole. (This description of stellar motions also applies to the southern hemisphere except all stars south of the celestial equator move around the south celestial pole.)

Figure 5-2

All stars appear to rotate around the celestial poles. However, the appearance of this motion varies depending on where you are looking in the sky. Near the north celestial pole the stars scribe out recognizable circles centered on the pole (1). Stars near the celestial equator also follow circular paths around the pole. But, the complete path is interrupted by the horizon.

These appear to rise in the east and set in the west (2). Looking toward the opposite pole, stars

curve or arc in the opposite direction scribing a circle around the opposite pole (3).

Advanced Series GT, C6-R, C6-RGT specifications

The Celestron C6-RGT and C6-R models, part of the Advanced Series GT lineup, are popular choices for amateur astronomers seeking high-quality optics and reliable features. The C6-RGT, equipped with a 6-inch refractor, is designed for both visual and astrophotographic pursuits. Its impressive features make it a great option for anyone looking to explore the night sky in greater detail.

One of the standout characteristics of the C6-RGT is its large 6-inch aperture, which allows for exceptional light-gathering capability. This feature is crucial for viewing faint celestial objects, giving users the ability to observe details in nebulae, galaxies, and star clusters. The refractor design minimizes chromatic aberration, ensuring sharp and clear images across a wide range of viewing conditions.

The telescope comes with a fully multi-coated optics system that enhances light transmission and contrast, creating brighter and clearer images. The C6-R is also designed with a robust aluminum tube that not only ensures durability but also helps maintain stability during long observing sessions.

The Advanced Series GT mount is another essential element of the C6-RGT and C6-R models. This computerized mount features a sturdy, stable design that supports a wide range of telescopes while providing smooth tracking of celestial objects. The GoTo technology allows users to locate and track over 40,000 celestial objects with ease. This high level of automation is particularly helpful for beginners who may be unfamiliar with the night sky.

Another notable feature of the Advanced Series GT is its ability to be controlled through a smartphone or tablet, thanks to Celestron's SkyPortal app. This integration opens doors for enhanced stargazing experiences, offering customizable tours and educational information right at your fingertips.

In terms of usability, both models have a comfortable height and the mount can be easily adjusted to accommodate various observing positions. The telescope is also portable, making it convenient for outreach events or trips to dark-sky locations.

Overall, the Celestron C6-RGT and C6-R models, with their combination of powerful optics, advanced technology, and user-friendly features, represent an excellent choice for both budding astronomers and passionate enthusiasts. With Celestron’s commitment to quality and innovation, these telescopes promise to deliver unforgettable views of the wonders of the universe.