mean sidereal day

简明释义

平均恒星日

英英释义

例句

1.Astronomers use the length of a mean sidereal day to calculate celestial events.

天文学家使用恒星日的长度来计算天文事件。

2.The rotation of the Earth relative to the stars defines a mean sidereal day.

地球相对于恒星的自转定义了一个恒星日。

3.The concept of a mean sidereal day is crucial for navigation in astronomy.

在天文学中，恒星日的概念对导航至关重要。

4.A mean sidereal day is approximately 23 hours, 56 minutes, and 4 seconds long.

一个恒星日大约是23小时、56分钟和4秒长。

5.To synchronize telescopes, scientists often refer to the mean sidereal day.

为了同步望远镜，科学家们经常提到恒星日。

作文

The concept of a mean sidereal day is fundamental in understanding the movement of celestial bodies and the measurement of time in astronomy. A mean sidereal day is defined as the average time it takes for the Earth to rotate once on its axis relative to the distant stars. This period is approximately 23 hours, 56 minutes, and 4 seconds. Unlike the solar day, which is based on the position of the Sun in the sky, the mean sidereal day provides a more consistent measure of time for astronomers observing the heavens.To grasp the significance of the mean sidereal day, one must first understand the Earth's rotation. The Earth rotates around its axis, completing one full rotation approximately every 24 hours. However, because the Earth is also orbiting around the Sun, the time it takes for the Earth to rotate once relative to the Sun is slightly longer than the time it takes to rotate relative to the stars. This discrepancy leads to the difference between the solar day and the mean sidereal day.The mean sidereal day is crucial for astronomers who need precise measurements for their observations. When astronomers locate a star in the night sky, they often refer to its position relative to the sidereal time. The sidereal clock, which measures time based on the mean sidereal day, helps them determine when a particular star will be visible in the sky. This is particularly important for telescopes that are tracking celestial objects, as they must compensate for the Earth's rotation in order to maintain focus on a target.Moreover, the mean sidereal day has practical applications beyond astronomy. For instance, satellite navigation systems, such as GPS, rely on precise timing to calculate positions accurately. These systems use atomic clocks that are calibrated using the mean sidereal day to ensure that the timing is consistent with the rotation of the Earth relative to the stars. This synchronization is essential for providing accurate location data to users worldwide.In addition to its scientific implications, the mean sidereal day also serves as a reminder of the vastness of the universe and the intricate mechanisms that govern celestial movements. It highlights how our perception of time is influenced by both our planet's rotation and its journey around the Sun. As we study the cosmos, understanding the mean sidereal day allows us to appreciate the complexity of the universe and our place within it.In conclusion, the mean sidereal day is an essential concept in astronomy and timekeeping. By providing a consistent measure of time based on the Earth's rotation relative to distant stars, it plays a vital role in astronomical observations and satellite navigation. As we continue to explore the universe, the significance of the mean sidereal day will remain a key aspect of our understanding of time and space. Whether we are stargazing or relying on technology for navigation, the mean sidereal day connects us to the cosmos and enhances our appreciation for the wonders of the universe.

“平均恒星日”的概念在理解天体运动和天文学中时间测量方面是基础性的。平均恒星日被定义为地球相对于遥远星体自转一周所需的平均时间。这个周期大约为23小时56分钟4秒。与基于太阳在天空中的位置的太阳日不同，平均恒星日为观察天空的天文学家提供了更一致的时间测量。要理解平均恒星日的重要性，首先必须了解地球的自转。地球围绕其轴自转，每大约24小时完成一次完整的自转。然而，由于地球也在围绕太阳公转，因此地球相对于太阳的自转时间略长于相对于星星的自转时间。这种差异导致了太阳日和平均恒星日之间的区别。平均恒星日对需要精确测量以进行观察的天文学家至关重要。当天文学家在夜空中定位一颗星星时，他们通常会参考其相对于恒星时间的位置。根据平均恒星日测量的恒星时钟帮助他们确定特定星星何时可见。这对于追踪天体的望远镜尤其重要，因为它们必须补偿地球的自转，以保持对目标的聚焦。此外，平均恒星日还在天文学之外具有实际应用。例如，卫星导航系统（如GPS）依赖于精确的计时来准确计算位置。这些系统使用原子钟，使用平均恒星日进行校准，以确保计时与地球相对于星星的自转保持一致。这种同步对于向全球用户提供准确的位置数据至关重要。除了科学意义外，平均恒星日还提醒我们宇宙的浩瀚以及支配天体运动的复杂机制。它突显了我们对时间的感知如何受到我们星球自转和绕太阳轨迹的影响。当我们研究宇宙时，理解平均恒星日使我们能够欣赏宇宙的复杂性以及我们在其中的位置。总之，平均恒星日是天文学和计时中的一个重要概念。通过提供基于地球相对于遥远星体自转的一致时间测量，它在天文观察和卫星导航中发挥着至关重要的作用。随着我们继续探索宇宙，平均恒星日的重要性将仍然是我们对时间和空间理解的关键方面。无论我们是在观星还是依赖技术进行导航，平均恒星日都将我们与宇宙连接在一起，并增强我们对宇宙奇观的欣赏。