The Bible seems to be clear that the Sabbath was created for man on the Seventh day of creation.
"And on the seventh day God ended His work which He had done, and He rested on the seventh day from all His work which He had done. Then God blessed the seventh day and sanctified it, because in it He rested from all His work which God had created and made." - Genesis 2:2,3
"And He said to them, 'The Sabbath was made for man, and not man for the Sabbath. Therefore the Son of Man is also Lord of the Sabbath.' " - Mark 2:27,28
The Bible also seems clear that there are other inhabited worlds that God created.
"God, who at various times and in various ways spoke in time past to the fathers by the prophets, has in these last days spoken to us by His Son, whom He has appointed heir of all things, through whom also He made the worlds." - Hebrews 1:1,2
"Now there was a day when the sons of God came to present themselves before the LORD, and Satan also came among them." - Job 1:6
"Again there was a day when the sons of God came to present themselves before the LORD, and Satan came also among them to present himself before the LORD." - Job 2:1
So the Bible says that Jesus created worlds, and in Job we find the heads of these worlds coming before God as well as Satan coming as the head of this world, a position originally given to Adam.
"Then the devil, taking Him up on a high mountain, showed Him all the kingdoms of the world in a moment of time. And the devil said to Him, 'All this authority I will give You, and their glory; for this has been delivered to me, and I give it to whomever I wish. Therefore, if You will worship before me, all will be Yours.' " - Luke 4:5-7
"Now is the judgment of this world; now the ruler of this world will be cast out." - John 12:31
So the Bible is clear that Satan is/was the "ruler" of this world (at least until Christ died on the cross and bought it back). Though, in actuality, it always belonged to God.
"For every beast of the forest is Mine, and the cattle on a thousand hills. I know all the birds of the mountains, and the wild beasts of the field are Mine. If I were hungry, I would not tell you; for the world is Mine, and all its fullness." - Psalm 50:10-12
The Bible also says that the Sabbath will continue throughout the ceaseless ages of eternity in heaven.
"'For as the new heavens and the new earth which I will make shall remain before Me,' says the LORD, 'So shall your descendants and your name remain. And it shall come to pass that from one New Moon to another, and from one Sabbath to another, all flesh shall come to worship before Me,' says the LORD." - Isaiah 66:22,23
This is not intended to be a discussion regarding these points of theology. This question is directed to Adventists who already have a correct understanding of what the Bible says about the Sabbath and about the structure of God's heavenly kingdom.
Do other worlds observe the Sabbath? Did the Sabbath exist before the seventh day of creation? Will all worlds keep the Sabbath throughout eternity?