The Edge of Two Worlds
Our planet draws closer to passing behind the Moon in this image captured by the Artemis II crew during their lunar flyby, about six minutes before Earthset.
SCIENCE DIVISIONS
Discover how we're driving the Nation's scientific progress through world-class research across Earth and Space sciences at Goddard’s Sciences and Exploration Directorate.
Earth Sciences
The Earth Sciences Division is the nation's technical innovator and essential data provider to support national infrastructure, scientific leadership, and economic resilience.
CODE 610
Go to Division
Astrophysics
The Astrophysics Science Division leads America's quest to answer our most profound scientific questions, developing technologies with transformative applications in medicine, national security, and intelligence.
CODE 660
Go to Division
Heliophysics
The Heliophysics Science Division advances understanding of the Sun and its interactions with Earth and the solar system, providing the foundational science that drives space weather research and solutions in collaboration with government, industry, and academia.
CODE 670
Go to Division
Planetary Sciences
The Solar System Exploration Division powers space missions and leads human space exploration to the Moon and Mars through revolutionary research that charts the frontiers of our solar system and deepens our understanding of planetary system formation and evolution.
CODE 690
Go to Division
Artemis II Science on Console
ASTRONOMY PICTURE OF THE DAY
The Retrograde Dance of Saturn and Neptune
What does it mean for Saturn and Neptune to be in retrograde? Featured is a composite of images taken over 34 nights from May 2025 to February 2026 tracing Saturn (brighter, foreground) and Neptune (dimmer, background). Over that time, the two planets exhibited retrograde motion, meaning they appeared to move backward in the sky. This apparent backwards motion occurs when Earth overtakes the slower outer planets as they orbit the Sun. Imagine the Solar System is a running track. Earth "runs" faster along the inside of the track compared to the outer planets. As Earth approaches, aligns, and then "laps" the outer planets, they change position from ahead to behind from the Earth's perspective. This perspective shift is what causes the outer planets to change position in the night sky. An animation corresponding to today’s image shows Saturn and Neptune’s months-long dance across the northern night sky. Saturn stepped from the Pisces constellation into Aquarius and back again while Neptune remained in Pisces. This is the closest Saturn and Neptune have been in the sky since their last conjunction in 1989.