Expires Aug 31, 2017 Online only
Only valid for new subscribers. Promo code provides 50% discount on monthly subscription fee after 30 day free trial concludes. Cannot be combined with any other offers, promotions or discounts (other than 30 day free trial). Offer FB50 must be redeemed by 8/31/17 at 11:59 PM ET exclusively through SmithsonianEarthTV.com. Apply promo code at check out.
SOURCE: Offer link: https://www.facebook.com/SmithsonianEarth/posts/1930525287160350