KHALED: Stars, planets and the moon all shine at night.
Why do they shine?

ALAN: Well, there're different reasons.
Stars like the sun produce and radiate their own light.
On the other hand, planets like earth and the satellite like
our moon do not have their own light. Planets and
satellites only reflect light. Stars radiate their own light
but the moon only reflect light.

KHALED: So, why is the moon brighter than stars?

ALAN: The moon is brighter because
it's too much closer to the stars.
The stars are really very far away.

KHALED: If you look in the sky at night, you can
often see a lot of stars.
How many stars are there in the sky?

ALAN: Well, scientists say there are
a hundred billion stars in our galaxy but we can only
see some of them.

KHALED: What does galaxy mean?

ALAN: A galaxy is a very large group of stars.
There're a million of galaxies in the universe
but we aren't able to see them.

KHALED: Do you think life exist
anywhere else in the universe?

ALAN: I don't know.
No body can know for sure.

What is a galaxy ?
ما هي المجرة
It is a body in space which has millions of stars .
جسم في الفضاء بها الملايين من النجوم

What is a star ?
ما هو النجم
It is a body in space which reflects light .
جسم في الفضاء يعكس الضوء

What is a satellite ?
ما هو القمر الصناعي؟
It is a body which orbits a planet
جسم يدورحول كوكب

What is a planet ?
ما هو الكوكب؟
It is a body which orbits a star.
جسم يدور حول نجم


Why are stars not as bright as the moon ?
لماذا النجوم ليست كسطوع القمر؟
Because they are very far in space .
لأنها بعيدة في الفضاء

How many planets does the solar system have ?
كم عدد الكواكب في المجموعة الشمسية ؟
It has nine planets
تسعة كواكب
تنبيه: مؤخراً تم إبعاد أحد الكواكب من المجموعة وبذلك يكون عددهم ثمانية

What are the inner planets ?
ما هي الكواكب الداخلية
They are the four planets which are nearest to the sun
and they have solid surface . They are Mercury , Venus , Earth , Mars .
الأربعة كواب القريبة من الشمس ذو سطوح صلبة
وهم عطار، الزهرة، الأرض و المريخ

How long does the Earth take to orbit the sun ?
كم المدة التي تستغرقها الأرض للدوران حول الشمس
It takes 365 days .
365 يوم

How long does the Earth take to spin round its own axis ?
كم تستغرق الأرض للدوران حول محورها؟
It takes 24 hours .
24 ساعة

What does the Earth’s atmosphere consist of ?
مم يتكون الغلاف الجوي للأرض؟
It consists of nitrogen , oxygen,
water vapour and some other gases .
النيتروجين ، الأكسجين، بخار الماء وبعض الغازات الأخرى

Why does the Earth have seasons ?
ما سبب وجود فصول مناخية على الأرض ؟
Because its axis is not vertical .
It is tilted at an angle of about 23º
لأن محورها غير عمودي. إنه مائل بدرجة 23 درجة

Why is Earth a unique planet ?
ما الذي يجعل الأرض كوكبا فريدا من نوعه
Because it has an atmosphere which
contains oxygen and water vapour .
لأنها تحتوي على غلاف جوي يتكون من الأكسجين وبخار الماء
It has a solid surface and it has seasons .
والأرض سطح صلب وفيه فصول مناخية