In Duluth you have two types of weather – “warmer over the hill” and “colder by the lake”. It can be a pleasant 75 degrees with a light breeze on the hill during the spring and early summer months. On the same day, a seven-minute drive downtown to the shore of Lake Superior shocks the senses. Winds blast from the east with temperatures in the low 50s. You don’t want to get caught without a jacket close at hand in this town.
NASA’s Voyager 1 space probe is making a similar journey from the cool comforts of the solar system to the energetic boundary of interstellar space. Launched in 1977, the craft flew past Jupiter in 1979 and Saturn in 198o, returning beautiful images and making amazing discoveries. Voyager 1 and its twin, Voyager 2, discovered the rings of Jupiter, sulfur volcanoes on the moon Io, lightning and aurora on the giant planets, more than a 1000 ringlets around Saturn and many new moons.
Today they’re still chugging away at the fringe of the solar system known as the heliosheath, a region of space where the sun’s influence wanes and the stars take over.
At 11.1 billion miles from Earth, Voyager 1 is the farthest man-made object from Earth. Just to radio data back to NASA’s Deep Space Network antennas, the transmission time requires 16 hours and 38 minutes traveling at the speed of light.
Our sun gives off a steady stream of charged particles – electrons and protons – in the form of the solar wind. The wind creates a gigantic bubble called the heliosphere around the solar system that defines the sun’s domain. All the planets, comets and asteroids we know of orbit within the heliosphere.
The wind blows outward for billions of miles before slowing down and heating up when it reaches a boundary called the termination shock. Beyond the boundary is the narrow heliosheath, a buffer zone between the sun’s influence and the frontier of interstellar space. Yes, we’re talking the space between the stars. Space ruled by the whims of the galaxy, untouched by the sun’s warm hand.
Voyager 1 crossed the termination shock in December 2004 and has been cruising through the heliosheath since. The sun’s steady wind shields the solar system from many of the cosmic rays created by exploding supernovae. The rays, actually high-speed subatomic particles, bound about the Milky Way like cosmic superballs. Once Voyager zoomed beyond the termination shock, the number of galactic cosmic ray hits has been steadily increasing. Starting on May 7, the numbers took a sudden leap, hinting that the probe may be on the verge of true interstellar space.
Perhaps it’s just now sensing the bow shock shown in the diagram above, the region where the interstellar wind slams into the solar. We’ll find out soon when data from two other instruments aboard Voyager 1 is crunched in the coming weeks. If so, this would be a significant, cradle-leaving step for humanity. Even if we can’t be there in person, this flying machine, a remote extension of ourselves, lets us travel beyond the home hearth to the wild void we always strain to hear.
Heads up! China successfully launched three astronauts including its first female into orbit earlier today. After a time orbiting Earth, the Shenzhou 9 craft will dock with the Tiangong 1 laboratory module. Two of the astronauts will live and work inside the module while the other stays aboard the main ship.
While we may not be able to see the docking from the U.S. (Tiangong 1 is not making visible passes) we can still catch the current series of evening passes of the International Space Station (ISS) which will be wind up in about a week. Times below are for the Duluth, Minn. region. For local times to watch for your city, please log in to Heavens Above or key in your zip code at Spaceweather’s Satellite Flyby page. The ISS travels from west to east across the sky.
* Tonight June 16 starting at 10:23 p.m. across the northern sky. Second pass at midnight when the station will disappear into Earth’s shadow when high in the south. Binoculars will show it change color from yellow-white to sunset red.
* Sunday June 17 at 11:05 p.m. Brilliant pass high in the north
* Monday June 18 at 10:11 p.m. in the north. Second short appearance in the west at 11:47 p.m.
* Tuesday June 19 at 10:53 p.m. Brilliant pass high in the south