Hubble’s last look at
85. before perihelion
ISON
Here Hubble has taken its closest look at the innermost region of the ISON comet,
where geysers of sublimating ice are fueling a spectacular tail.
Made from observations on November 2, 2013, the round coma around ISON’s
nucleus is blue and the tail has a redder hue. Ice and gas in the coma reflect blue
light from the Sun, while dust grains in the tail reflect more red light than blue light.
This is the most colour separation seen so far in ISON and the comet, nearer than
ever to the Sun, is brighter and more structured than ever before.
Comet ISON came closest to the Sun on November 28, a point in its orbit known as
perihelion. Comet ISON was fairly quiet until November 1, when it experienced an
outburst that doubled the amount of gas the comet emitted. After this image was
taken, a second outburst shook the comet, increasing its activity by a factor of ten.
Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
Mysterious
86. old spiral
This striking cosmic whirl is the centre of galaxy NGC 524, located in the
constellation of Pisces, some 90 million light-years from Earth.
NGC 524 is a lenticular galaxy. Lenticular galaxies are believed to be an
intermediate state in galactic evolution — they are neither elliptical nor
spiral. Spirals are middle-aged galaxies with vast, pinwheeling arms that
contain millions of stars. Along with these stars are large clouds of gas
and dust that, when dense enough, are the nurseries where new stars
are born. When all the gas is either depleted or lost into space, the arms
gradually fade away and the spiral shape begins to weaken. At the
end of this process, what remains is a lenticular galaxy — a bright disc
full of old, red stars surrounded by what little gas and dust the galaxy
has managed to cling on to.
This image shows the shape of NGC 524 in detail, formed by the
remaining gas surrounding the galaxy’s central bulge. Observations
of this galaxy have revealed that it maintains some spiral-like motion,
explaining its intricate structure.
Credit: ESA/Hubble & NASA