5 things you need to know Wednesday
1. Letterman says sayonara to light-night TV
On Wednesday night, David Letterman will host his final Late Show. He's seen a slew of celebrity guests in the past few weeks. (George Clooney handcuffed himself to Letterman so the host couldn't retire.) For his last show, Letterman will say sayonara with highlights, surprise guests, a final Top Ten list, and presumably, even stupid pet tricks. When the TV camera's red light goes dark on Wednesday, Letterman's dream job will come to an end. The gig, Letterman told Alec Baldwin in 2012, has allowed the Indianapolis native to do exactly what he wanted across 33 years and more than 6,000 episodes of late-night talk.

2. Hubble starts to paint a picture of space – 25 years later
25 years ago on Wednesday, NASA's Hubble Space Telescope sent back its first photo of outer space. Since then, Hubble has provided us with some of the most detailed images ever of our solar system, our galaxy, and our universe, allowing a deep view into space and time. As NASA administrator Charlie Bolden said recently, "Hubble has fundamentally changed human understanding of the universe and our place in it."

3. Ellis Island reopens to tell the whole story of immigration
About 12 million immigrants were processed in the Ellis Island's Great Hall, but there's a story to tell of immigration to the U.S. before the Ellis Island processing station opened in 1892 and after it closed in 1954. On Wednesday, The Ellis Island Museum will officially become the Ellis Island National Museum of Immigration. The center breaks the story down into four parts: the journey to America, struggle and survival after arrival, efforts to build communities, and becoming citizens.

4. Tweet @Dominos to order a pizza
It's no gimmick, Domino's says Twitter is a permanent option for ordering pizza starting Wednesday. Yes, customers can tweet @Dominos to get a pizza. Regulars will only need to tweet the pizza emoji. It's all about attracting busy, younger consumers, and the pizza delivery behemoth already has upward of 50% of its sales taking place digitally. For Twitter, it's an evolution that the online social network is trying to make from a place to chat about or even advertise stuff to a place where folks can buy stuff.
5. Odd couple to blast into space
An unlikely pair of spacecraft are set to take off Wednesday morning: the Air Force's secretive X-37B space plane and a citizen-funded solar sailing experiment that has been bolstered by Bill Nye the Science Guy. The military plane's mission is classified and is a part of a program moving its operations from California to Kennedy Space Center in Cape Canaveral, Fla. In contrast, the LightSail mission was funded by members of the nonprofit Planetary Society, of which Nye is CEO. The LightSail will be in orbit for about a month. Launch time is 11:05 a.m. ET.
And, the essentials:
Weather: The sodden Plains will see more rain and the chance for flooding on Wednesday as cooler air spreads over the Great Lakes and Northeast.

Stocks: U.S. stock futures were higher Wednesday.
TV Tonight: Wondering what to watch tonight? TV critic Robert Bianco looks at Mysteries of Laura and David Letterman's final Late Show.
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