“Heaven” or “Heavens” in Genesis 1:1?

"In the beginning God created the heaven and the earth." (Genesis 1:1, KJV)

Critics charge that שמים (shamayim) is plural and should be translated as “heavens.” In Hebrew, however, the plural form may identify size rather than number in certain contexts. Such a plural is called a "plural of extension or amplification" (William Rosenau, Hebraisms in the Authorized Version of the Bible, p. 111).  Even in English, the plural form, "skies," is used to refer to a large expanse in the atmosphere which is technically just one sky (e.g. "The plane took to the skies"). Jewish translations of the Tanakh also translate שמים (shamayim) in Genesis 1:1 as “heaven.” The New JPS Translation According to the Traditional Hebrew Text says, “heaven.” The 1917 JPS Translation says, “heaven.” Moreover, just a few verses later in Genesis 1:8 the NASB and ESV translate שמים as “heaven.” The NIV translates it as “sky” (singular). The translators of the NASB, ESV, and NIV all agree that שמים can be translated in the singular. Whether the word should be translated in the singular or plural depends on the translator’s assessment of the context. The KJV translators translated שמים in Genesis 1:1 in the singular because the other heaven (the expanse in the sky) was not created until day two (Genesis 1:7-8).