What is "mi'Ketze ha'Shamayim Motza'o"?
Radak, Malbim: It comes out (rises) from the east [end of Shamayim].
What is "u'Sekufaso Al Ketzosam"?
Rashi: It is going around from one end to the other.
Radak #1: Its path encompasses all ends of Shamayim. It goes around all directions and returns to where it rose - "Holech El Darom v'Sovev El Tzafon" (Koheles 1:6). During the day we see it traverse the south, and at night it traverses the north (Eruvin 56a), and returns to [east], where it rose. This is how it appears to us. It does not truly go to the southern end; it only leans to the south.
Radak #2: According to astronomy, this refers to the sun's annual path (refer to 19:6:1:4). It is in the south in winter, and in the north in summer (Pirkei d'R. Eliezer 6).
Malbim: It does not travel straight over the equator. Rather, it goes around to the ends, i.e. north and south. This shows the great Chachmah [in Hashem's creation]! If it always traveled straight over the equator, the world could not be settled. At the equator would be too hot, and its heat would not reach the north and south at all. Rather, it goes to all ends, and its heat reaches the entire world, and it is all proper to be settled.
Why does it say "v'Ein Nistar me'Chamaso"?
Vayikra Rabah (16:8): When it is very hot, there is no escape from the sun's heat 1 (as opposed to the cold, which one can escape through wearing more garments).
Rashi: If the sun were in the lowest Raki'a, one would not be able to escape its heat. There are seven Reki'os; the sun, moon, stars and Mazalos are in the second (Chagigah 12b).
Rashi (8): There is no escape from its heat on the day of judgment - "v'Lihat Osam ha'Yom ha'Ba" (Mal'achi 3:19). However, "Toras Hashem Temimah Meshivas Nafesh" (verse 8) - it returns the soul to the ways of life, and protects those who learn it from the flame - "v'Zarchah Lachem Yir'ei Shmi Shemesh Tzedakah u'Marpei" (Mal'achi 3:20).
Radak: The sun is in the entire world, even though it is not equally [strong] everywhere. One can hide from its light, but not from its heat, which penetrates even to inner rooms 2 .
Radak citing Ibn Ezra: The sun's heat in the world is like the heart's heat in the body, which is essential for life. Nothing is hidden from benefit from its heat.
