Just Passing By


On 10 April, the ESA BepiColumbo spacecraft flew by Earth during a gravity assist maneouver on its way to Mercury. This 360-degree VR simulation of the flyby  takes you on a trip past Earth at the distance of only 12,700 km. The simulation displays the fields of view a pair of BepiColombo’s science instruments (MERTIS and PHEBUS) and two of its three MCAM selfie cameras.

Video Credit: ESA

Twilight


earthterminator_iss002_920This picture was taken from the International Space Station orbiting at an altitude of 390 km. The terminator is the line between day and night. In pictures of  airless moons it’s a firm line, but no such sharp boundary marks the division between day and night in this picture of ocean and clouds on Earth. Instead, the shadow line is diffuse and shows the gradual transition to darkness as twilight falls. The Sun illuminates the scene from the right, and the cloud tops reflect gently reddened sunlight filtered through the troposphere, the lowest layer of the atmosphere. The upper atmosphere scatters blue sunlight and fades into the blackness of space.

Image Credit: NASA

That Pale Blue Dot


This is an updated version of the Pale Blue Dot image taken by the Voyager 1 spacecraft 30 years ago today. It was created using modern image-processing software and techniques while trying to remain faithful to the original. Like the original, this new color view shows the Earth as a single blue pixel in the vastness of space. Rays of sunlight scattered within the camera optics stretch across the scene, one of which intersects with Earth. Look closely at the stripe just right of center. That speck a bit past half way up isn’t dust on your screen. It’s the Earth.

The image was taken just before Voyager 1’s cameras were turned off to conserve power because the probe would not make another planetary flyby. Shutting down instruments and other systems on the two Voyager spacecraft has been a gradual and ongoing process that has helped keep them running as they have left the Solar System.

Image Credit: NASA

Earthshine


This video takes us around the Moon and shows how it is illuminated not only by the brilliant light of the Sun but also by light reflected from the Earth. The trip starts on the side facing away from Earth where part of the surface is brightly illuminated by the Sun but the rest is totally dark. Moving around the Moon, the Earth rises, and its reflected bluish light illuminates the Moon’s surface. This dull glow is the earthshine. (You can clearly see it from Earth when the Moon appears as a crescent in the evening or morning sky.) When the Sun emerges from behind the Moon, the brilliant crescent is seen, but the earthshine is still faintly visible.

Video Credit: ESO

Spring Has Sprung …


… here in the Northern Hemisphere. The equinox occurred last week. At an equinox Earth’s terminator, the dividing line between day and night, runs through the planet’s north and south poles as seen at the start of this time-lapse video which crams an entire year into twelve seconds. It was put together using Meteosat infrared images taken every day at the same local time from a geosynchronous orbit. The video actually starts at the September 2010 equinox. As the Earth revolves around the Sun, the terminator tilts as less daily sunlight falls on the northern hemisphere, reaching the solstice and northern hemisphere winter at the maximum tilt. As the year continues, the terminator tilts back again to the March 2011 equinox halfway through the video. Then the terminator swings past the poles, until the June 2011 solstice, the start of northern summer. The video ends as the September equinox returns.

Video Credit: NASA / Meteosat / Robert Simmon

Just Passing By


Because the amount of energy necessary for an interplanetary flight is available from practical launch vehicles, spacecraft often use a planet’s gravity to provide some of the energy needed for final trajectories. Properly executed, one or more gravity assist flybys can be enough to change a spacecraft’s speed and direction so it can enter orbit around another world or fly off into the Kuiper Belt or even interstellar space.

This view of Earth was captured in 2007 on the second of three Earth flybys made by ESA’s comet-chasing Rosetta spacecraft on its ten year journey to Comet 67P/Churyumov-Gerasimenko.

Image Credit: ESA

Earthshine


This video takes us around the Moon and shows how it is illuminated not only by the brilliant light of the Sun but also by light reflected from the Earth. The trip starts on the side facing away from Earth where part of the surface is brightly illuminated by the Sun but the rest is totally dark. Moving around the Moon, the Earth rises, and its reflected bluish light illuminates the Moon’s surface. This dull glow is the earthshine. (You can clearly see it from Earth when the Moon appears as a crescent in the evening or morning sky.) When the Sun emerges from behind the Moon, the brilliant crescent is seen, but the earthshine is still faintly visible.

Video Credit: ESO

You Are Here


earth-from-mars-hiresThe most powerful telescope orbiting Mars took this view of Earth and its Moon, showing continent-size detail on the planet. The image combines two separate exposures taken last November by the High Resolution Imaging Science Experiment (HiRISE) camera on the Mars Reconnaissance Orbiter. The images were taken to calibrate HiRISE  using the known value of reflectance for the Earth-facing side of the Moon. The exposures used to make this composite image were processed separately to optimize detail visible on both Earth and the Moon. The Moon is much darker than Earth and would barely be visible if shown at the same brightness scale as Earth.

The combined view retains the correct positions and sizes of the two bodies relative to each other. The distance between Earth and the Moon is about 30 times the diameter of Earth. Earth and the moon appear closer than they actually are in this image because the observation was planned for a time at which the Moon was almost directly behind Earth as seen from Mars so that the Earth-facing side of the Moon would be visible.

The reddish feature near the middle of the face of Earth is Australia. Mars was about (205 million km from Earth when the images were taken.

Image Credit: NASA

An EPIC View


This animation was put together from images showing the Moon moving across the  DISCOVR satellite’s view of the Earth. The images were taken by the Earth Polychromatic Imaging Camera (EPIC). The satellite is in orbit 1,000,000 miles from the Earth. That’s just over 4X the radius of the Moon’s orbit.

[youtube https://www.youtube.com/watch?v=DMdhQsHbWTs]

Video Credit: NASA

Leaving Home


What it would look like to leave the Earth? The MESSENGER spacecraft took the images that make up this time-lapse video while it was on its way toward the planet Mercury. Earth is seen rotating as it recedes into the distance.

[youtube http://www.youtube.com/watch?v=rFDjAfwmWKM]

Image Credit: NASA

You Are Here—In Color


earth-moon_from_saturnLast Friday, the Cassini spacecraft was able to take a picture of the Earth from the spacecraft’s orbit around Saturn. This morning, I posted a black-and-white portion of this larger view taken by Cassini‘s wide-angle camera. Here’s the entire image. Click it to embiggen. Go ahead. It’s worth it. You can use your back button to return.

The dark side of Saturn, its bright limb, the main rings, the F ring, and the G and E rings are visible. The limb of Saturn and the F ring are overexposed. The “breaks” in the brightness of Saturn’s limb are shadows of the rings The E and G rings have been brightened through post processing for better visibility.

Earth, which is 1.44 billion km away in this image, is that blue dot indicated by the arrow. In the full-size image the Moon can be seen as a fainter protrusion off its right side. The other bright dots are stars

This is only the third time that Earth has been photographed from the outer solar system.

Image Credit: NASA

You Are Here


earthmoon_cassini_960This is the Earth-Moon system as seen by the Cassini spacecraft orbiting Saturn in the outer Solar System. Earth is the larger of the two spots near the center; the Moon is to its lower left. This raw, unprocessed image shows several streaks that are not stars. They are cosmic rays that struck the digital camera while it was taking the image. The image was taken by Cassini on Friday.

Image Credit: NASA