The term we know as heaven is the English translation of the original two words in the Bible. The Hebrew word in the Old Testament is pronounced roughly shaw-may, and the Greek word in the New Testament is pronounced roughly, oo-ran-aws. Both mean the same thing - either the sky, or the outer space above it, depending on the context of what the writer was talking about. Sky or space are quite accurate modern substitutes for heaven.
Signs In The Heavens
Prior to The Return Of Jesus Christ, there are going to be many spectacular events occurring from space, for all the world to see. A few examples:
"something like a great mountain, burning with fire, was thrown into the sea; and a third of the sea became blood, a third of the living creatures in the sea died, and a third of the ships were destroyed." (Revelation 8:8-9 RSV) (see Flying Mountains)
"The third angel blew his trumpet, and a great star [i.e. a comet, perhaps similar to that shown in the photograph] fell from heaven, blazing like a torch, and it fell on a third of the rivers and on the fountains of water. The name of the star is Wormwood. A third of the waters became wormwood, and many men died of the water, because it was made bitter." (Revelation 8:10-11 RSV)
"The fourth angel blew his trumpet, and a third of the sun was struck, and a third of the moon, and a third of the stars, so that a third of their light was darkened; a third of the day was kept from shining, and likewise a third of the night." (Revelation 8:12 RSV) (see The Seven Seals)
The Return Of Jesus Christ
The Return Of Jesus Christ will not be secret or hidden. All the world will witness the event:
"For The Lord Himself will descend from heaven with a cry of command, with the archangel's call, and with the sound of the trumpet of God. And the dead in Christ will rise first; then we who are alive, who are left, shall be caught up together with them in the clouds to meet The Lord in the air." (1 Thessalonians 4:16-17 RSV) (see The Last Day)
"And The Lord will become king over all the earth; on that day The Lord will be one and His Name one." (Zechariah 14:9 RSV)
"They Will Make War On The Lamb"
"And the ten horns that you saw are ten kings who have not yet received royal power, but they are to receive authority as kings for one hour, together with the beast. These are of one mind and give over their power and authority to the beast; they will make war on the Lamb, and the Lamb will conquer them, for He is Lord of lords and King of kings, and those with Him are called and chosen and faithful." (Revelation 17:12-14 RSV) (see Daniel's Statue)
Fact Finder: Will Jesus Christ return from heaven in the same way that He ascended?
See also The Mount Of Olives