Scientists have found that a chameleon is able to rapidly change color because of tiny crystals directly under the skin that act as mirrors.

In a study published Tuesday in Nature Communications, researchers shared that panther chameleons have crystals called iridophores that contract or expand if the chameleon is feeling excited or stressed, and reflect different wavelengths of light. "Light will bounce on them only for specific wavelengths," co-author Michel Milinkovitch told BBC Earth. "The other wavelengths will not bounce on these cells."

The different colors are caused by the size of the crystals and where they are on the skin. Male chameleons change color frequently to show off for a rival or to scare him away. "It's really a social display," Milinkovitch said. The researchers also found a deeper layer of skin that reflects near-infrared sunlight, and might be responsible for helping chameleons regulate body temperatures. Catherine Garcia

The Senate will this coming week consider President Trump's Saturday proposal for an immigration deal to end the government shutdown, Senate Majority Leader Mitch McConnell said Saturday — but the pitch is unlikely to gain much traction with House Speaker Nancy Pelosi (D-Calif.) and congressional Democrats more broadly.

"Democrats were hopeful that the President was finally willing to re-open government and proceed with a much-need discussion to protect the border," Pelosi said in a statement released right before Trump's remarks began. "Unfortunately, initial reports make clear that his proposal is a compilation of several previously rejected initiatives, each of which is unacceptable and in total, do not represent a good faith effort to restore certainty to people's lives.“

Trump's plan offers three years of relief, including from deportation, for recipients of Deferred Action for Childhood Arrivals (DACA) and temporary protected status (TPS), but Pelosi's statement demands a "permanent solution." She also asks for increased port of entry infrastructure and more customs agents, which Trump did not mention.

However, there is some overlap between the two lists. Both Pelosi and Trump call for more immigration judges and border patrol agents as well as, in Trump's words, "drug detection technology to help secure our ports of entry."

Pelosi's statement concludes with a request that Trump re-open the government so comprehensive immigration policy negotiations can proceed. Trump's speech ended by urging Congress to agree to his deal to re-open the government so "weekly bipartisan meetings at the White House" can be scheduled for immigration policy reform. Bonnie Kristian

President Trump began his address on border security and the partial government shutdown Saturday with a grim description of the "humanitarian and security crisis on our southern border." He highlighted the dangers of migrants' journeys to the United States, especially sexual assault, and argued stricter border control would reduce crime and drug trafficking.

"As I candidate for president, I promised I would fix this crisis, and I intend to keep that promise one way or the other," Trump said. "I am here today to break the logjam and provide Congress with a path forward to end the government shutdown and solve the crisis on the southern border."

That path, as Trump explained it, includes "$800 million in urgent humanitarian assistance, $805 million for drug detection technology to help secure our ports of entry, an additional 2,750 border agents and law enforcement professionals, [and] 75 new immigration judge teams to reduce the backlog of — believe it or not — almost 900,000 cases."

The proposal retains Trump's longstanding demand of $5.7 billion for construction of "powerful and fully designed, see-through steel barrier[s]" in "high-priority locations." It offers "three years of legislative relief for 700,000 [Deferred Action for Childhood Arrivals (DACA)] recipients brought here unlawfully by their parents at a young age," as well as a "three-year extension of temporary protected status (TPS)" for "300,000 immigrants whose protective status is facing expiration" while further immigration reform is negotiated.

Trump also listed two "measures to protect migrant children from exploitation and abuse," a "new system to allow Central American minors to apply for asylum in their home countries and reform to promote family reunification for unaccompanied children" detained away from their families in the United States.

"That is our plan: border security, DACA, TPS, and many other things," Trump concluded. "This plan solves the immediate crisis ... and immediately re-opens our federal government." Watch the full live stream below. Bonnie Kristian

"We have made a lot of progress as far as denuclearization is concerned and we are talking about a lot of different things. Things are going very well with North Korea," President Trump told reporters Saturday of his Friday conversation with North Korean negotiator Kim Yong Chol.

"That was an incredible meeting," Trump said. "We've agreed to [another summit between Trump and North Korean leader Kim Jong Un], probably the end of February. We've picked a country, but we'll be announcing it in the future. Kim Jong Un is looking very forward to it and so am I."

Vietnam, Thailand, and Singapore are thought to be under consideration for the summit's location. Read a "plausible roadmap to peace with North Korea" from The Week's Harry J. Kazianis here. Bonnie Kristian

At least 66 people were killed and dozens more injured Friday when a fuel pipeline in Mexico exploded after being ruptured by fuel thieves. Some 85 people not included in the current death toll are listed as missing as of Saturday morning.

A crowd of people had gathered to collect the spilling fuel in plastic containers when the fireball occurred. Local authorities said the death toll could continue to rise given the severity of the injuries and the number of people whose whereabouts remain unknown.

Illegal pipeline taps like this one, which occurred near the town of Tlahuelilpan about 60 miles north of Mexico City, are a chronic problem in Mexico; an average of 42 taps were drilled daily in the first 10 months of 2018. "Far from stopping the fight ... against fuel theft, it's going to become stronger," said Mexican President Andres Manuel Lopez Obrador on Saturday. "We'll continue until we've eradicated these practices." Bonnie Kristian

Jason Van Dyke, the Chicago police officer convicted of second-degree murder and 16 counts of aggravated battery for his fatal shooting of a black teenager named Laquan McDonald in 2014, was sentenced Friday to six years and nine months in prison.

With good behavior, Van Dyke could be out of custody in three years or less, his lawyer said. The special prosecutor who handled the case had requested a sentence of 18 to 20 years, and the sentence Van Dyke received is for the murder charge alone, not the battery. Each of the battery convictions had a mandatory minimum sentence of six years, and the judge could have ordered them to be served sequentially.

On Thursday, three other officers accused of falsifying reports to justify the shooting were acquitted. Bonnie Kristian

For once, President Trump is really happy with Special Counsel Robert Mueller.

He responded with a flurry of tweets Friday and Saturday to Friday evening's news that Mueller denied a BuzzFeed News report alleging his investigation had compiled evidence Trump directed Michael Cohen, his former personal attorney, to lie to Congress about the Moscow Trump Tower project.

Many of Trump's posts were retweets from friendly voices like his eldest son, Donald Trump Jr., and commentator Geraldo Rivera:

In his own tweets, Trump called the BuzzFeed report "disgraceful" and blamed it for a "very sad day for journalism."

Trump also tweeted on familiar topics including the Steele Dossier, the stock market, immigration, and his perceived persecution at the hands of the press. Bonnie Kristian