OpenGL glBegin and glPushMatrix - c

Question

I try to design a scene with 3 spheres and one line horizontal as equator. I got to draw the 3 spheres but I don't know why the line is not draw.
This is my code, for if you can see where I'm wrong:
#include <GL/gl.h>
#include <GL/glut.h>
void render(void);
void reshape(int w, int h);
int angle = 90;
int main(int argc, char **argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowPosition(50, 50);
glutInitWindowSize(800, 600);
glutCreateWindow("Planets");
glutDisplayFunc(render);
glutReshapeFunc(reshape);
glutMainLoop();
return 0;
}
void render(void) {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glClearColor(0, 0, 0, 1);
// Equator
glBegin(GL_LINES);
glColor3f(1,1,1);
glLineWidth(1);
glTranslated(0, 0, 0);
glVertex2f(0, 2);
glVertex2f(2,2);
glEnd();
// Sun
glPushMatrix();
glLoadIdentity();
glColor3f(1.0, 1.0, 0.0);
glTranslated(0, 0, -2);
glRotated(angle, 1, 0, 0);
glutWireSphere(.3, 20, 20);
glPopMatrix();
//Earth
glPushMatrix();
glLoadIdentity();
glColor3f(0.0, 0.0, 1.0);
glTranslated(0.7, 0, -2);
glRotated(angle, 1, 0, 0);
glutWireSphere(.15, 20, 20);
glPopMatrix();
// Moon
glPushMatrix();
glLoadIdentity();
glColor3f(1.0, 0.0, 1.0);
glTranslated(1, 0, -2);
glRotated(angle, 1, 0, 0);
glutWireSphere(.05, 10, 10);
glPopMatrix();
glutSwapBuffers();
}
void reshape(int w, int h) {
const double ar = (double) w / (double) h;
glViewport(0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glFrustum(-ar, ar, -1.0, 1.0, 2.0, 100.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}

Answer 1

You specify a frustum that has the near clip plane at z=-2. Your intended line would be drawn at z=0, thus outside the projection volume, thereby clipped into non-rendering.
glTranslate(0,0,0) is a no-op BTW.