المستندات والموارد - نتائج البحث
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Horizontal Coordinate System
صورة
أُنشئ لصالح OAE
الشرح: This image shows the horizontal coordinate system of an observer on Earth. On the right we see the coordinate system in the local context of the observer. The observer appears here as a point surrounded by the celestial sphere. The ground appears as a plane, while the Earth is round, we can approximate the ground in the area around the observer as a plane. The line where this plane intersects with the celestial sphere is the horizon. The point directly above the observer is the zenith, the point directly below the observer is the nadir which is hidden by the ground.
Two coordinates define this coordinate system, altitude and azimuth, hence the reason this sometimes called an alt-az coordinate system. The altitude is zero at the horizon, maximum (90°) at the zenith and minimum (-90°) at the nadir. Azimuth is the angle around the horizon. Most commonly this is defined to be zero in the direction of north. Any point on the celestial sphere can be defined by these two coordinates. However what objects appear on these position will depend on the time and the location of the observer.
On the left-hand part of the diagram, we can see that when we put the observer and their local horizontal coordinate system in a global context, that the parts of the sky the observer can see depend on their position on the Earth and on the rotation of the Earth. The zenith points perpendicular to the Earth's surface so the position on the sky the zenith and nadir correspond to is dependent on the observer's latitude. The horizon also depends on the observer's position on the Earth.
المصدر: Maria Cristina Fortuna/IAU OAE
مصطلحات المعجم:
الارتفاع , السَّمت , الأفق , السمت , النَّظِير
فئات:
علم الفلك بالعين المجردة
, علم الفلك الرصدي
الترخيص: المشاع الإبداعي نَسب المُصنَّف 4.0 دولي (CC BY 4.0) المشاع الإبداعي نَسب المُصنَّف 4.0 دولي (CC BY 4.0) أيقونات
ملف
( صورة
1.76 MB)
ملف PDF
(PDF file
165.78 kB)
Also available in black and white
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483.06 kB)
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136.70 kB)
Celestial Coordinates
صورة
أُنشئ لصالح OAE
الشرح: Here we see how celestial coordinates map positions on the celestial sphere. The celestial sphere is an imaginary, hollow sphere that surrounds the Earth. Celestial objects appear to be attached to the inside of the celestial sphere, and the planets, Sun, and Moon appear to move slowly across it.
The celestial sphere has a spherical coordinate system similar to the latitude and longitude we see on the Earth. The celestial equator is the projection of the Earth's equator onto the celestial sphere while the north and south celestial poles are the projections of the Earth's north and south poles onto the celestial sphere.
Declination is similar to latitude on the Earth in that it marks the angle above and below the celestial equator. Declination is zero on the celestial equator, is positive to the north of the celestial equator and negative to the south of it. It is commonly measured in degrees and sometimes in radians.
Right Ascension is similar to longitude as it marks the angle around the celestial equator. As with longitude the zero point of right ascension (shown here as a dashed line) is a matter of choice. Traditionally the zero point of right ascension was the position of the Sun at the northern hemisphere vernal equinox (spring equinox) in March. It is positive and increases to the east, unlike longitude on Earth which is defined as east or west of the prime meridian. It is most commonly measured in hours, minutes and seconds or occasionally in degrees or radians.
The ecliptic marks the Sun's path across the celestial sphere when viewed from the Earth.
The Earth rotates within the celestial sphere. This leads to objects like stars or galaxies, which appear static on the celestial sphere, rising and setting when viewed from the Earth but remaining in the same position on the celestial sphere.
The Earth's axis precesses within the celestial sphere. This slowly moves the celestial equator and the celestial poles meaning that the traditional celestial coordinate system changes slowly over time meaning that stars and galaxies that do not move will have positions that change. Astronomers have used coordinate systems defined by the position of the celestial poles and equator at a fixed point in time. Now celestial positions are most commonly measured on a fixed coordinate system defined by the position of the celestial poles and equator on the 1st of January 2000.
المصدر: Maria Cristina Fortuna/IAU OAE
فئات:
علم الفلك بالعين المجردة
, علم الفلك الرصدي
الترخيص: المشاع الإبداعي نَسب المُصنَّف 4.0 دولي (CC BY 4.0) المشاع الإبداعي نَسب المُصنَّف 4.0 دولي (CC BY 4.0) أيقونات
ملف
( صورة
517.83 kB)
ملف PDF
(PDF file
203.59 kB)
Also available in black and white
ملف
( صورة
501.79 kB)
ملف PDF
(
202.13 kB)
Evening Sky Watching for Students نشاط تعليمي astroEDU (رابط إلى موقع astroEDU) Origin: astroEDU الوصف: Let's observe the evening sky with the naked eye
مصطلحات المعجم:
التلوث الضوئي , الرصد الفلكي
فئات:
علم الفلك الرصدي
, كوكب الأرض
وسوم:
Art
, Motion of star
, Observation of sky
, Sky watching
الفئات العمرية:
4-6
, 6-8
المرحلة التعليمية:
مرحلة ما قبل المدرسة
, المرحلة الابتدائية
مجالات التعلم:
مجموعات نقاش
, قائم على الملاحظة
, تعلم منظم قائم على الاستقصاء
التكاليف:
مجاني
المدة:
30 دقيقة
حجم المجموعة:
جماعي
المهارات:
طرح الأسئلة
, توصيل المعلومات
المؤلفون: Akihiko Tomita
الترخيص: المشاع الإبداعي نَسب المُصنَّف 4.0 دولي (CC BY 4.0) المشاع الإبداعي نَسب المُصنَّف 4.0 دولي (CC BY 4.0) أيقونات
