Drones are all the rage now, but can you imagine one the size of a bug?

Meet the RoboBee X-Wing, a new robot created by scientists at Harvard University. Standing under three inches tall, with a wingspan of less than two inches, this tiny machine flaps its little wings 170 times a second. It also runs on solar power, starting to fly whenever its solar cells are exposed to light. This makes it the lightest device ever to fly without being attached to an external power source, New Scientist reports.

Currently, it's not quite ready to be flying outdoors — it needs light three times as intense as sunlight, so it needs some improvements before it can embark on its first real expedition. But one day, the RoboBee might be used to monitor the environment, or get into spaces too small for people or other robots. At its size, it's even light enough to "land on a leaf," said Noah Jafferis, one of the RoboBee's creators.

You can read the study detailing the RoboBee X-Wing's capabilities at Nature, or watch it fly below. Shivani Ishwar

Using a remote sensing method, scientists working in southern Mexico found an ancient structure that has a total volume exceeding Egypt's Great Pyramid of Giza.

The discovery in Aguada Fénix is the largest and oldest-known structure built by the Maya civilization, Reuters reports. A rectangular elevated platform made of clay and earth, it was built between 1000 and 800 BC, is nearly a quarter-mile wide and nine-tenths of a mile long, and stood 33 to 50 feet high.

Researchers used Light Detection and Ranging, or Lidar, to find the structure. Lidar is a remote sensing method used to examine the surface of the Earth and measure ranges. This technique uses laser light and other data recorded by an aerial system to generate three-dimensional information about the surface.

University of Arizona archeologist Takeshi Inomata led the research, published Wednesday in Nature, and told Reuters the structure is "so large horizontally, if you walk on it, it just looks like natural landscape." Researches believe it was used "for special occasions, possibly tied to calendrical cycles. The rituals probably involved processions along the causeways and within the rectangular plaza. The people also deposited symbolic objects such as jade axes in the center of the plateau." Catherine Garcia

President Trump responded to Wednesday's blistering rebuke from former Defense Secretary James Mattis by attacking the reticent retired four-star Marine general in two factually challenged tweets.

Mattis, who retired from the military in 2013, sent a statement to The Atlantic on Wednesday lambasting Trump's leadership. He argued that Trump ordered U.S. military personnel to violate the Constitution for his "bizarre photo op" in front of a church, said he hasn't offered "mature leadership," and compared Trump's content attempts to "divide us" to the Nazi "divide and conquer" ethos. "We do not need to militarize our response to protests," Mattis wrote. "We need to unite around a common purpose. And it starts by guaranteeing that all of us are equal before the law."

Trump, recycling old attacks, called Mattis "the world's most overrated general," stated incorrectly that he fired him — Mattis resigned in protest of Trump's decision to pull U.S. forces out of Syria, abandoning Kurdish allies — and claimed falsely that he was the one who gave Mattis the hated nickname "Mad Dog."

Mattis and Trump never had a great working relationship, but after resigning with a dryly critical letter, he told The Atlantic there's "a period in which I owe my silence" to the president and his former colleagues, but "it's not eternal. It's not going to be forever." The period is evidently over, and there may be more to come.

Mattis isn't the only retired military leader criticizing Trump's military deployment in the capital and threat to send active-duty troops to other cities — former Joint Chiefs chairmen Adm. Mike Mullen and Martin Dempsey criticized Trump's military response to lawful protests on Tuesday, and a former top Pentagon official, James N. Miller, resigned from the Defense Science Board in protest. Peter Weber

Tropical Storm Cristobal made landfall on Wednesday near Atasta in the Mexican state of Campeche, bringing heavy rain that is expected to last through Thursday.

The storm formed Tuesday from the remnants of Pacific Tropical Storm Amanda, which left 22 people dead in Guatemala and El Salvador. At least 138 people were evacuated from Campeche by the Mexican army, due to high floodwaters. Forecasters say Cristobal will likely become a tropical depression by Thursday, before moving back to the Gulf of Mexico on Friday.

Cristobal could reach the U.S. Gulf Coast on Sunday, but the U.S. National Hurricane Center said "the model guidance currently suggests that the atmospheric environment over the Gulf will not be very conducive for strengthening." Catherine Garcia

California Gov. Gavin Newsom (D) is calling President Trump's threat to send the military to major cities "just another zig and zag deflection from the administration."

On Monday, Trump warned that if governors and mayors didn't do enough to quell protests, he would send "thousands and thousands of heavily armed soldiers, military personnel, and law enforcement officials" to cities. Newsom brushed aside the threat, telling reporters on Wednesday, "It won't happen. It's not going to happen. We would reject it. We would push back against that."

Following requests from mayors like Eric Garcetti of Los Angeles, Newsom has deployed 2,600 California National Guard troops to some parts of the state. Catherine Garcia

AMC, the largest theater chain in the U.S., said Wednesday it may not be able to survive the coronavirus pandemic.

AMC theaters were shut down in March, and the chain said in a regulatory filing that it has enough cash to reopen all of them in the summer, but if that can't happen, it will need more money.

The company listed several concerns, including whether customers are even going to want to return to theaters during the pandemic. Since March, some new movies have been released to streaming platforms for at-home viewing, and AMC and other theater chains are worried this practice will continue in the future. Because Hollywood has stopped production on movies, it will also take time before there are full slates of new films.

Due to all of this, AMC expressed "substantial doubt" of its "ability to continue" for an extended period of time. The company has 1,000 theaters in the U.S. and Europe. Catherine Garcia

In a stinging rebuke, Former Defense Secretary James Mattis criticized President Trump's response to peaceful protests, saying he is "the first president in my lifetime who does not try to unite the American people — does not even pretend to try. Instead, he tries to divide us. We are witnessing the consequences of three years of this deliberate effort. We are witnessing the consequences of three years without mature leadership."

Mattis, a retired Marine general, resigned in 2018 in response to Trump's decision to withdraw U.S. troops from eastern Syria. He broke his silence on Trump's behavior Wednesday, telling The Atlantic in a statement that watching protesters get tear gassed in Lafayette Square and hearing Trump threaten to use the military to crush demonstrations left him "angry and appalled."

The protests are "defined by tens of thousands of people of conscience who are insisting that we live up to our values — our values as people and our values as a nation," he said. The forceful removal of demonstrators in Lafayette Square for Trump's "bizarre" photo op in front of St. John's Church was an "abuse of executive authority," he said, and "we must reject and hold accountable those in office who would make a mockery of our Constitution."

The country can still come together without Trump, "drawing on the strengths inherent in our civil society," Mattis said. It won't be easy, "but we owe it to our fellow citizens, to past generations that bled to defend our promise, and to our children." Read more at The Atlantic. Catherine Garcia