1904 : The Potsdam Great Refractor with a spectrograph detects interstellar medium.
The binary star Mintaka in Orionis determined to have the element calcium in the intervening space.

January 1959: Luna 1 becomes the first spacecraft to observe the solar wind.

1962: Mariner 2 detects the solar wind.

1972–1973: Pioneer 10 becomes the first spacecraft to explore the heliosphere past Mars, flying by Jupiter on 4 December 1973 and continuing to return solar wind data out to a distance of 67 AU.

February 1992: After flying by Jupiter, the Ulysses spacecraft becomes the first to explore the mid and high latitudes of the heliosphere.

1992: Pioneer and Voyager probes detected Ly-α radiation resonantly scattered by heliospheric hydrogen.

2004: Voyager 1 becomes the first spacecraft to reach the termination shock.

2005: SOHO observations of the solar wind show that the shape of the heliosphere is not axisymmetrical, but distorted, very likely under the effect of the local galactic magnetic field.

2009: IBEX project scientists discover and map a ribbon-shaped region of intense energetic neutral atom emission.
These neutral atoms are thought to be originating from the heliopause.

October 2009: the heliosphere may be bubble, not comet shaped.

October 2010: significant changes were detected in the ribbon after 6 months, based on the second set of IBEX observations.

May 2012: IBEX data implies there is probably not a bow "shock".

June 2012: At 119 AU, Voyager 1 detected an increase in cosmic rays.

25 August 2012: Voyager 1 crosses the heliopause, becoming the first human-made object to depart the heliosphere.

August 2018: long-term studies about the hydrogen wall by the New Horizons spacecraft confirmed results first detected in 1992 by the two Voyager spacecraft.

5 November 2018: Voyager 2 crosses the heliopause, departing the heliosphere.
1904 : The Potsdam Great Refractor with a spectrograph detects interstellar medium. The binary star Mintaka in Orionis determined to have the element calcium in the intervening space.
January 1959: Luna 1 becomes the first spacecraft to observe the solar wind.
1962: Mariner 2 detects the solar wind.
1972–1973: Pioneer 10 becomes the first spacecraft to explore the heliosphere past Mars, flying by Jupiter on 4 December 1973 and continuing to return solar wind data out to a distance of 67 AU.
February 1992: After flying by Jupiter, the Ulysses spacecraft becomes the first to explore the mid and high latitudes of the heliosphere.
1992: Pioneer and Voyager probes detected Ly-α radiation resonantly scattered by heliospheric hydrogen.
2004: Voyager 1 becomes the first spacecraft to reach the termination shock.
2005: SOHO observations of the solar wind show that the shape of the heliosphere is not axisymmetrical, but distorted, very likely under the effect of the local galactic magnetic field.
2009: IBEX project scientists discover and map a ribbon-shaped region of intense energetic neutral atom emission. These neutral atoms are thought to be originating from the heliopause.
October 2009: the heliosphere may be bubble, not comet shaped.
October 2010: significant changes were detected in the ribbon after 6 months, based on the second set of IBEX observations.
May 2012: IBEX data implies there is probably not a bow "shock".
June 2012: At 119 AU, Voyager 1 detected an increase in cosmic rays.
25 August 2012: Voyager 1 crosses the heliopause, becoming the first human-made object to depart the heliosphere.
August 2018: long-term studies about the hydrogen wall by the New Horizons spacecraft confirmed results first detected in 1992 by the two Voyager spacecraft.
5 November 2018: Voyager 2 crosses the heliopause, departing the heliosphere.
Heliosphere