The Islamic State group-inspired attacks were among the deadliest in Sri Lanka's history, killing 42 foreigners.

(Image credit: Eranga Jayawardane)

CNN, MS NOW and Politico have sued Trump after the networks were suspended from the White House. And, Paramount makes concessions to resolve a lawsuit over its massive Warner Bros. Discovery merger.

(Image credit: Alex Wroblewski)

As the U.S. conflict with Iran drags, the Iranian-backed Houthis in Yemen have opened a new front, taking new territory and displacing more than 100,000 people.

(Image credit: Mohammed Huwais)

A lock of hair, 15 years of sleuthing and a 200-year-old question. In History by a Hair, Smithsonian Institution scholar Richard Kurin follows the DNA trail back to Thomas Jefferson.

Students in New Hampshire will hear from NASA astronaut Anil Menon as he answers prerecorded STEM questions while aboard the International Space Station.

The Earth-to-space call will begin at 11:35 a.m. EDT Thursday, Sept. 24, and will stream live on the agency’s Learn With NASA YouTube channel.

This event is hosted by the McAuliffe-Shepard Discovery Center in Concord, New Hampshire, for students in grades K-12, and members of the community. This unique opportunity aims to deepen understanding of space exploration and enhance awareness of STEM careers.

Media interested in covering the event must RSVP no later than 5 p.m. EDT, Wednesday, Sept. 23, to Kelly Thompson at kthompson@starhop.com.

For more than 25 years, people have lived and worked continuously aboard the International Space Station, advancing scientific knowledge and making research breakthroughs not possible on Earth. The space station helps NASA understand and overcome the challenges of human spaceflight, expand commercial opportunities in low Earth orbit, and build on the foundation for long-duration missions to the Moon, as part of the Artemis program, and to Mars.

For more information on NASA in-flight calls, visit:

https://www.nasa.gov/stemonstation

Explore More

2 min read

NASA Kicks Off Nationwide Effort to Prepare Tomorrow’s Space Workforce

Article 18 hours ago

2 min read

Johnson Space Center Sparks Curiosity at Houston’s 33rd Annual Japan Festival  

Article 1 day ago

2 min read

NASA Awards SpaceX Three Crew Flights to Space Station

To continue regular crew transportation to the International Space Station, NASA has awarded SpaceX three…

Article 4 days ago

Keep Exploring

Discover Related Topics

Missions

Humans in Space

Climate Change

Solar System

Most kids learn in elementary school that the seasons are caused by Earth rotating on a tilted axis during its yearly orbit around the Sun. The substantial tilt, about 23.5 degrees, is thought to be the result of an ancient planetary body, Theia, smashing into Earth about 4.5 billion years ago, in the same cataclysmic collision that formed the Moon.

To visualize why Earth has seasons, imagine the planet as a spinning top tilted to one side. Around the June solstice, the Northern Hemisphere leans toward the Sun, bringing more direct sunlight and longer days. Around the December solstice, the Southern Hemisphere does the same. That’s why June ushers in summer and warm weather in the Northern Hemisphere, while December does so in the Southern Hemisphere.

The March and September equinoxes serve as the midpoints between these two seasonal extremes. On those days, the terminator—the boundary between the sunlit and dark sides of Earth—runs directly through both poles. As a result, the Northern and Southern Hemispheres receive almost the same amount of sunlight, and day and night are nearly equal in length.

What do the seasons look like from about one million miles away? That’s the view provided by NASA’s EPIC (Earth Polychromatic Imaging Camera) aboard the NOAA mission DSCOVR (Deep Space Climate Observatory). By maintaining an orbit that puts the spacecraft between the Sun and Earth roughly 1.6 million kilometers (1 million miles) from Earth, the camera has a nearly continuous view of the sunlit hemisphere. As Earth spins during the course of a day, EPIC captures a full-disk image of the planet’s sunlit face every few hours.

The four images above, taken at roughly the same time of day, show how EPIC’s view of the Western Hemisphere changes over the year, from the December solstice (upper left) to the March equinox (upper right), June solstice (lower left), and September equinox (lower right). The most striking difference is between the two solstices. In December, South America lies near the center of the disk and much of Antarctica is visible, while North America is partially out of view. In June, Earth’s tilt means the situation is reversed: the Northern Hemisphere and North America are more centered, Arctic sea ice comes into view, South America is offset, and Antarctica is completely out of view.

There are other notable differences among the four images. Earth looks slightly smaller during the March and September equinoxes, for instance. That’s because DSCOVR was tens of thousands of miles farther away from Earth on those dates than on the solstices. On December 21, 2023, DSCOVR was 1,447,327 kilometers (899,327 miles) from Earth compared with 1,561,901 kilometers (970,520 miles) on September 22, 2024.

The slight difference in Earth’s apparent size has nothing to do with Earth’s tilt. Instead, it occurs because DSCOVR follows a looping, three-dimensional path called a Lissajous orbit to keep the spacecraft near Lagrange point 1, where the combined gravitational pull of the Sun and Earth and the centrifugal pull of the satellite balance out, making it easier for engineers to maintain the spacecraft’s position without using much fuel. DSCOVR’s distance from Earth swings between its maximum and minimum roughly every three months, and the timing drifts throughout the year because of lunar influences and orbital maneuvers. In 2024, the orbit happened to put the spacecraft slightly farther from Earth at both equinoxes, but that is not always the case.

There’s one other notable way the images differ. Because of DSCOVR’s Lissajous orbit, the angle between the Sun, Earth, and satellite varies between 2 and 12 degrees, explained Alexander Marshak, the deputy project scientist for the DSCOVR mission. Earth appears as a fully illuminated disk at smaller angles and less rounded at larger angles, like a “bite” has been taken out, similar to a gibbous phase of the Moon. For this set of images, the September 22 image has a slightly lower angle (8.1°) than the December 21 image (10.3°), making it appear slightly rounder and fuller. The angle between the Sun, Earth, and satellite in the other two images is between 9° and 10°.

“You can see the subtle influence of the changing orbital geometry in these images,” Marshak said. “But the most obvious changes—the apparent location of the continents—are due to Earth’s tilt.”

EPIC’s vantage point offers a perspective that makes it easier to understand and visualize why Earth has seasons, but after more than a decade in space, the mission has also opened up new approaches to understanding and observing how daily and seasonal cycles play out on a planetary scale. It has collected more than a decade of diurnal and seasonal data on many key features on Earth, including vegetation, clouds, ice, snow, UV radiation, ocean color, and aerosols.

NASA Earth Observatory image by Michala Garrison, using data from DSCOVR EPIC. Story by Adam Voiland.

Downloads

December 21, 2023
March 19, 2024
June 20, 2024
September 22, 2024

JPEG (3.07 MB)

References & Resources

• Kostinski, A., et al. (2024) Deep space observations of conditionally averaged global reflectance patterns. Frontiers of Remote Sensing, 5, 1404461.
• Kostinski, A., et al. (2021) Deep space observations of terrestrial glitter. Earth and Space Science, 8, e2020EA001521.
• Lyapustin, A., et al. (2026) Editorial: Earth observations from the deep space: 10 years of the DSCOVR mission. Frontiers in Remote Sensing, 7, 1810164.
• NASA (2026, June 19) Earth Polychromatic Image Camera. Accessed September 21, 2026.                                                                                                                                                 
• NASA Earth Observatory (2011, September 23) Seeing Equinoxes and Solstices from Space. Accessed September 21, 2026.
• NASA (2026) EPIC: Publications. Accessed September 21, 2026.
• NASA Scientific Visualization Studio (2012, December 27) Earth Orientation Animations. Accessed September 21, 2026.
• NASA Space Place (2026, July 31) What Causes the Seasons? Accessed September 21, 2026.
• Roberts, C., et al. (2015) Early Mission Maneuver Operations for the Deep Space Climate Observatory Sun-Earth L1 Libration Point Mission. Accessed September 21, 2026.
• Valero, F., et al. (2021) Lagrange Point Missions: The Key to next Generation Integrated Earth Observations. DSCOVR Innovation. Accessed September 21, 2026.

You may also be interested in:

Stay up-to-date with the latest content from NASA as we explore the universe and discover more about our home planet.

A Moonlit Earth as Seen From Artemis II

4 min read

An astronaut’s photo, taken en route to the Moon, reveals our planet and its place in space in a novel…

Article

June 2026 Satellite Puzzler

2 min read

Your challenge is to tell us the location of the satellite image and why it is interesting.

Article

Great Balls of Fire

4 min read

An astronaut on the International Space Station was surprised to photograph a shower of light streaking through the darkness while…

Article

Keep Exploring

Discover More from NASA Earth Science

Subscribe to Earth Observatory Newsletters

Subscribe to the Earth Observatory and get the Earth in your inbox.

Earth Observatory Image of the Day

NASA’s Earth Observatory brings you the Earth, every day, with in-depth stories and stunning imagery.

Explore Earth Science

Earth Science Data

Open access to NASA’s archive of Earth science data

3 Min Read

Embracing the Equinox

Depending on your locale, equinoxes can be seen as harbingers of longer nights and gloomy weather, or promising beacons of nicer temperatures and more sunlight. Observing and predicting equinoxes is one of the earliest skills in humanity’s astronomical toolkit. Many ancient observatories around the world observed equinoxes along with the more pronounced solstices. These days, you don’t need your own observatory to know when an equinox occurs, since you’ll see it marked on your calendar twice a year! The word “equinox” originates from Latin, and translates to equal (equi-) night (-nox). But what exactly is an equinox?

An equinox occurs twice every year, in March and September. In 2026, the equinoxes will occur on March 20, at exactly 14:46 UTC (or 7:46 AM EDT), and again on September 23, at 00:05 UTC (or September 22, 2026, at 5:05 PM PDT). The equinox marks the exact moment when the center of the Sun crosses the plane of our planet’s equator. The day of an equinox, observers at the equator will see the Sun directly overhead at noon. After the March equinox, observers anywhere on Earth will see the Sun’s path in the sky continue its movement further north every day until the June solstice, after which it begins traveling south. The Sun crosses the equatorial plane again during the September equinox, and continues traveling south until the December solstice, when it heads back north once again. This movement is why some refer to the March equinox as the northward equinox and the September equinox as the southward equinox.

Our Sun shines equally on both the Northern and Southern Hemispheres during equinoxes, which is why they are the only times of the year when the Earth’s North and South Poles are simultaneously lit by sunlight. Notably, the length of day and night on the equinox isn’t precisely equal; the date for that split depends on your latitude, and may occur a few days earlier or later than the equinox itself. The complicating factors? Our Sun and atmosphere! The Sun itself is a sphere and not a point light source, so its edge is refracted by our atmosphere as it rises and sets, which adds several minutes of light to every day. The Sun doesn’t neatly wink on and off at sunrise and sunset like a light bulb, and so there isn’t a perfect split of day and night on the equinox – but it’s very close.

Equinoxes are associated with the changing seasons. In March, Northern Hemisphere observers welcome the longer, warmer days heralded by their vernal, or spring, equinox, but Southern Hemisphere observers note the shorter days – and longer, cooler nights – signaled by their autumnal, or fall, equinox. Come September, the reverse is true.

Originally posted by Dave Prosper: February 2022

Last Updated by Kat Troche: March 2026

The Republic of Albania signed the Artemis Accords Monday during a ceremony hosted by NASA at the agency’s headquarters in Washington, joining the coalition of like‑minded nations committed to the responsible and transparent exploration of space.

“It is my privilege to welcome the Republic of Albania as the 73rd signatory of the Artemis Accords,” said NASA Deputy Administrator Matt Anderson. “The relationship between our nations goes back more than a century. Today, we extend that partnership into space.”

Albania’s Minister for Europe and Foreign Affairs Ferit Hoxha signed on behalf of the country. Ambassador of the Republic of Albania to the United States Ervin Bushati and the U.S. Deputy Assistant Secretary of State for Space and Environment Connor Tomlinson also participated in the event.

“It is a great honor for Albania to join the growing community of nations that have signed these important Artemis Accords,” said Hoxha in remarks during the ceremony. “By taking this step, Albania affirms its commitment to peaceful, transparent, sustainable, and cooperative exploration of space. We do so as a country deeply committed to international law, multilateral cooperation, and the belief that humanity’s greatest achievements are realized not in isolation, but through partnerships.”

Marking a significant step in Albania’s efforts to strengthen its use of space‑based data, Albania launched two dedicated Earth‑observation satellites, Albania‑1 and Albania‑2, in January 2023 aboard a SpaceX Falcon 9 rocket from NASA’s Kennedy Space Center in Florida, an example of how the United States is supporting Albania’s capabilities in space.

Albania also has played an active role in NASA’s Space Apps Challenge, hosting local events that connected students, technologists, and innovators with NASA’s openly available Earth and space science data. NASA Space Apps is the world’s largest annual global hackathon, mobilizing participants in more than 150 countries to develop creative solutions to real-world challenges using open data from NASA and partner space agencies to advance exploration for the benefit of all.

In 2020, NASA and the State Department joined with seven other founding nations to establish the Artemis Accords, responding to the growing interest in lunar activities by both governments and private companies. They introduced the first set of practical principles aimed at enhancing the safety and coordination between nations as they explore the Moon, Mars, and beyond, committing nations to: 

• Explore peaceably and transparently 
• Render aid to those in need 
• Enable access to scientific data 
• Ensure activities do not interfere with those of others 
• Preserve historically significant sites and artifacts by developing best practices 

By signing the Artemis Accords, nations open the door to opportunities for future lunar exploration with NASA, advancing humanity’s return to the Moon, and shaping the Golden Age of space exploration and innovation. 

Learn more about the Artemis Accords at:  

https://www.nasa.gov/artemis-accords