NASA’s Solar Dynamics Observatory captured this close-up image of an outburst on the sun's surface, between Nov. 3-5, 2015. Though the sun’s extreme ultraviolet light is invisible to our eyes, the wavelength is colorized here in red. (NASA/SDO)

2015 was a banner year for space exploration. Some of the stunning discoveries and most-memorable celestial images are rounded up in the slideshow above; it's a look back at a year spent among the cosmos.

In March, NASA launched its Magnetospheric MultiScale (MMS) mission into Earth's orbit, measuring the interaction between — or the powerful solar winds and geomagnetic storms emitting from the sun — and Earth's atmosphere. Studying these storms can help make our power system stronger against them in the future.

Later in the month of March, a revolutionary twin study examining the health effects of long-term space travel began. Astronaut Scott Kelly has lived in space aboard the International Space Station since March 27. He'll stay for a planned total of 340 days while his twin and fellow astronaut, Mark Kelly, remains on Earth. This will yield volumes of data on what it might take to send a manned mission to Mars, as well as otherlong-termmissions. Throughout the mission, Kelly's photos, tweeted from 220 miles above Earth's surface, enchanted viewers all year long.

In July, the New Horizons spacecraft made . New Horizons has transmitted images back to Earth in the months since, captivating scientists and enthralling the public with a view of the dwarf planet more complex than ever imagined.

Our study of the Red Planet continued to evolve in 2015. Scientists announced found on the surface of Mars in September. All year long, the Mars rovers continued their exploration of the planet's surface while the Mars Reconnaissance Orbiter collected data on and more.

Scientists also continued to probe into our solar system and the Milky Way galaxy, as well as hundreds of galaxies millions of light-years away.

In November, astronomers announced the discovery of the most-distant object in our solar system — three times farther than Pluto. Its orbit can't quite be explained “from what we know about the solar system,” Scott Sheppard, an astronomer at the Carnegie Institution for Science in Washington, D.C., told Scienceat the time of the announcement.

This quote represents the year in sum, and the way forward. As humanity pushes the boundaries of outer space, both in terms of distance and understanding, there's little doubt 2016 will produce a multitude of answers about the cosmos — and just as many questions.

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The ESO 3.6-meter telescope at La Silla observatory in Chile, during observations. (ESO/S. Brunier)